Engine dies randomly

[Driver915]

Alright I gotta start by saying that this forum has helped me with 90% of getting this truck back on the road after 25 years. You guys know your shit. Now onto the details.. I got a 1972 521 pickup with the original L16, California spec with the EVAP system, EGR system etc.. I put a Weber 32/36 carb on it and got rid of the valve in the engine bay controlling that EVAP system in the bed (Charcoal canister, vapor canister, I dunno what you wanna call it..). I wanted to block off that system since it's not useful and figure out how to just vent the tank, my mechanic said to just try leaving the canister hooked up without the stuff in the engine bay so I did that. Now to the problem. I got the thing on the road last night, cruised around the block a few times and it ran pretty well. Parked it in driveway, decided I wanted it in the garage, so I start driving it around and the thing dies right out the driveway as if it ran out of fuel. Like full throttle wasn't getting any fuel, didn't crank back up. It didn't have much fuel in it so I put a little in it, thing fired up and drove around the block again just fine. Let it sit overnight, started it this morning, running great again. Pull out of the garage, same thing happens, it dies as if it's out of fuel. This time it clearly isn't out of fuel cause I put 5 gallons of fresh gas in it out of a can before starting it, I pull the fuel line off of the carburetor crank it over and pump is pumping perfect. Again let it sit a moment it fires up and drove around town just fine. Had my mechanic set the ignition timing from the beginning and tune the carburetor so it ran for quite awhile with no issues in his shop. Get in it to go do a test drive, jump on the highway and it's running really damn good, dump it in 4th gear and it does the same thing and stalls out. Use the clutch as a starter while rolling and get the thing to barely sputter itself back to the house (about 2 blocks from where it died) then waited a few seconds and fire it up like nothing ever happened. Sorry if this is a long and hard to read post, I'm at a loss and figured I would explain the 4 times it died on me so far. I ran it for almost 2 hours one day on blocks while messing with the cooling system, charging system and other stuff and it never did this until I started driving it. Any ideas? Is the evap canister crap causing it to stop sucking fuel out of the tank? Does anyone know how to delete the evap system and properly vent the tank? When it's got fuel pressure and all the thing runs great so I don't see it being in the carburetor unless somehow it's using so damn much fuel that the pump can't keep the bowl full while actually driving.

[datzenmike]

As it has gas and it's being delivered to the carburetor it has to be the carburetor. Possibly something in the float chamber that randomly blocks the primary jet?

 

They say the 80% of carburetor problems are the electrical system and 80% of electrical problems are the carburetor.

 

So to eliminate the ignition, carry a spare spark plug in the truck, the next time it quits pull one of the plug wires off and stick the plug in the end, hold against the head to ground it and have a helper try to start the engine. Got spark?

 

Yes there is spark.... must be the carburetor.

No, there's no spark.... solve this random loss of ignition. Could be a thermal problem with the coil.

[Driver915]

I'll have to try that and see if it does anything funky in the ignition, considering how much I've run it without issues it seems weird but I haven't replaced any of it besides plugs so I could easily see it getting too hot when under load like driving. I see what you're saying though about it always being the opposite problem to what you think it is. Would it be worth tearing into that carburetor to see if anything isn't working right? It's a new carb, I bought and installed it about 2 months ago now. Redline kit off ebay. The truck has been running a ton since the carb was put on just never actually driving. Every time it died I pulled the air filter off and pulled the throttle and 2/3 times I saw fuel squirting down the carb, only once I couldn't see it for sure but I heard squirting so not sure. Reading my post again I'll touch back on the charcoal canister, could it be clogged or letting air where it shouldn't, causing air pockets in the fuel system? I never had the charcoal canister system hooked up when running it in the driveway, I just had the 2 ports coming from the tank blocked off and ran it with no fuel cap and it never had this problem but I know that wasn't the right way to have the tank hooked up hence why I reverted it. I know that system is really problematic and knowing the truck sat in a field the whole time it was parked it really wouldn't surprise me if the canister is full of garbage. And yes I did drop the tank, clean it out multiple times, replace all rubber lines aswell as blow out the hard lines before ever attempting to run the engine from the fuel system so I doubt it's rust from the tank. Both my filters are clear too.

[mklotz70]

LOL......I read through all of this thinking "debris in the tank".....right up to your last two sentences. 😞  

 

So...since it happened twice as you were leaving the driveway, is there a curb, bump or change in angle there?  

 

Intermittent problems like this are a real headache to find until they get so bad they're obvious.

 

It wouldn't hurt to take the top off the carb and look for debris in the carb.  Just like debris in the tank, it would sit dormant while idling or running in the driveway, but once the truck start moving, it can get jostled around enough to move into the fuel flow path.  You'd expect a new carb to not have an issue, but maybe there was some debris in it from manufacturing....?  

Hmmm.....did you put a new EGR valve on it?  If that were to intermittently stick open, it would cause a vacuum leak that would affect the running.  

 

If it dies slowly, it's probably gas related.  If it dies suddenly, it's probably ignition.  

 

With my first car, I "prettied up" the engine bay by using cable clamps to hold the wiring to certain areas and taping up things so there wasn't a bunch of loose wires flopping around.  I actually made things too tight.  The movement of the engine on the motor mounts ended up pulling a wire out of a connector.  If it was idling, it ran, but if I gave it too much gas or let out the clutch too fast, the motor would roll a bit and break the connection.  Boy, did that think buck for a bit until I figured it out.  Your problem certainly doesn't sound like this one, I just put it out there as an weird circumstance(example) to maybe help shift your perspective with your problem......to look at things that couldn't possibly be the problem. 

 

As for the evap....if things are blocked off at the engine so there's no vacuum leaks, the tank end won't matter much.  Gas caps these days are not vented because that's what their systems require.  Back in the day, if a non-vented cap was put on a sealed system, enough vacuum could be created in the tank to counter the pull of the fuel pump.  It's a really long stretch, but if that happened, it could work at low speeds and idle, but where more fuel is needed, it starves the carb.  When it sits for a period, enough air leaks in to let it run just fine.  It's pretty much a "hail mary pass", but since you've worked on the evap system, it came to mind.

 

Good luck!!

[datzenmike]

It's news to me that the 521 even had an EGR. Can't find it on the later '73 620 L16. Doesn't seem to be on the '73-'74 L18s but is on the L20Bs in the mid '70s.

 

If it has an EGR then the engine or intake was swapped? Or you are mistaking something for an EGR. All EGR had a pipe or tube from the exhaust manifold to the EGR valve mounted on the intake. Does yours?

 

Possible engine swap! Look on the top of the block for the engine ID. It's just behind the dip stick handle...

 

 

Head ID. Look along bottom edge of head below the #1 spark plug. This is a W58 but the L16 should be 210 ...

 

[Driver915]

I'll have to check into the wiring but I left it relatively loose so that nothing was strained like that and I could wiggle it if needed. Now that I think about it I never replaced the connector ends going into the distributor. Wonder if those are coming loose on bumps. Coming out of the driveway there is an angle change but not a severe one, just a dip at the very end where it hits the road. I'll give a look in the carb for debris. To explain again what exactly it's doing you'll be cruising along just fine then out of nowhere lose all power, and as the truck slows down the motor shuts off. If you push the clutch it shuts off instantly. I don't think it has an EGR valve besides the one going back to the fuel tank and I got rid of that, I'll go get pictures of that whole area, the truck came out of California with all the smog crap on it and it looks like an EGR system to me. I can't find anything about it besides some diagrams. All the vacuum on the engine has been either capped or routed where it normally goes so it should be ok there. The engine I'm convinced is the original L16. Truck was my grandfather's since new and I know he barely maintained it (it's clear through everything I've replaced so far.. and his other vehicles) and the motor was supposedly rebuilt once but never swapped that I know of. It may have never been rebuilt either, he had a stroke a few years after it was parked and couldn't remember why he parked it or exactly what he had done to it. It had a Nikki carburetor on it originally but I couldn't find a replacement and the original one looked like it had been buried so I didn't wanna try rebuilding it. That's why it has a Weber. I'll grab all those numbers off the motor for Mike and grab some pictures around the intake and such, maybe I did something wrong with the vacuum. I appreciate all these replies. First time I've ever tried reviving a car so it's been an experience for sure.

[Driver915]

Engine ID is L16-130238. Excuse how dirty it is I need to deep clean it badly. The last pic is an older one when I first put the Weber on it and you can see the valve and hoses on the fender that were leading to the fuel tank. Yes I kept the Kangaroo bag I didn't toss it. The washer motor was dead and I didn't wanna destroy the bag so I got a cheap ebay one. Maybe the old one should hang somewhere as wall art? Also the big hose going into the air filter is just the breather coming off of the valve cover. Was set up like that originally so I figured I would copy it.

[datzenmike]

 

Most definitely NO EGR on it.

 

The valve over on the inner left fender with hoses is called the Flow Guide Valve. It's benign and has no effect on running and should be kept.  It vents gas tank fumes and also allows air into the tank to replace the gas as it empties.

 

[mklotz70]

sorry guys.....I meant PCV.  I just don't do this stuff enough anymore to be of any help.  Not to hijack the thread, but my wife and I talked about selling her 521....not serious yet and no time soon.  Anyway....  I'll check back on this thread when I have time to read the rest of the posts.

[banzai510(hainz)]

why is that smaller hose under the carb hooked up to the crank vent.  all you did it by pass the PCV valve .  I would hook it up where it belongs. I think it goes to the tank vent but I dont even run them myself .

 

the hose that on thecrank case vent tube the small one goes to the valve on side of the inner fender lower spout. the top went to the aircleaner if I remember right. you can get rid of that upper hose.  the one under the master cylinder goes to the valve on the inner side of the fender again. You see it with the 3 spouts.

 

just plug that hole up where that 90deg elbow under the carb and see what happens.  cause when the motor get going faster it will suck air in. Really you think it would be like a cheap turbo sucking more gas in thru the top of the carb but the PCV valve would handle this(if im not mistaken).

 

when it stops running right then  open the hood and take the center coil wire from the Distributor and place near ground and start it. if you get spark then your good Its fuel related.  OK now when this happens imdeatly ck the carn and cycle the linkage with your hand and see if gas squirts in the carb thru the accell pump. If not then your running out of gas to the carb either the fuel pump or the needle valve  is dirty and it stuck closed.  If it was stuck open carb would flood out , that is NOT your proplem here.

 

 

just to let you kow I run 2 filter on my 521 as the tanks get dirt in there thru the fuel line filer tube by the band clamp. water can seep in there also cause rust.

My proplem I would loose idle . The idle jet would plug up cause of the rust. but since your idle is fine I think your good.

Mike said maybe the main jet could be plugged. I really dont think so but if thrue try running the truck with the choke on and see if better. what this does its enrich the carb thru the second barrel and kinda bypass the main jet on the other side.  if runs like it not running out of gas then your main fuel diliver seems to be ok.

 

I would also check your distributor as a hail marry if the dist bushing has lots of slop and will cause issues at higher rpm.

 

maybe something simple as a condensor not grounded in the points.  Long as you have the stock coil and ballast for your point system. dont run High Out coils unless it matches the system. actually can make it worse. if dont wrong will burn up points.

 

PS

GET A BATTERY HOLD DOW!!!!!!!!!!!!!!! one that wont short out as its near the positive terminal also

 

I have the same exact truck in green.

 

Love the rust Patina  hope you keep it that way

 

 

 

 

Edited August 26, 2023 by banzai510(hainz)

[mklotz70]

If you don't have a factory manual, there's a few places online to download them from(free).....here's one of them.

http://www.bluehandsvideo.com/manuals.html

 

[banzai510(hainz)]

another thing

remeber this

521 has fuse box issue also. usually corrossion from the wet.

 

I would replace the fuse just buy chance the ignition fuse is cracked on the end inside the fuse on the ends. Usally the solder joint can break. Not that this is your issue .

 

 

if you can find some one that has a L16 distributor single point  that has been converted to a Pertronix this would improve throuble shooting later .

Most people dont know how to care for points anymore and give up. Its a simple system but needs alot more care.  electronis is simple and most of the time care free. then one can say the ignition is good and go right for the carb

[banzai510(hainz)]

only other thought is the fuel pump you have looks stock. I know those are pretty much chinese clones that look good. Unless this is a brand new KOYO Senki japan unit in there

make sure you have the spacer in between the head and fuel pump. use the old one or there is one with the pump. No spacer will destroy the fuel pump arm.

[datzenmike]

 

The hose with the gear clamp on it as mentioned does not go to the block vent. That's a vacuum leak right there. Disconnect it and put a plug in the end. It originally probably went to the vacuum servo on the air filter snorkel. That's part of the ATC (automatic temperature control) that mixes warmed air with cold outside air to maintain a constant 90F all year round. You don't have the air filter or the plumbing so just plug the hose.

 

 

 

[Driver915]

I'll look into that small hose I didn't know that's what it was. I had it capped for awhile I don't remember when I connected it to the block vent. I'll cap it off again. What would you do with the block vent side, leave it open? As for battery hold down and fusebox the fusebox I replaced with a cheap Amazon one with blade fuses, the original one had a solder joint completely busted off on one post. And the battery is held down with a strap now. No way I'm leaving a loose battery in it. I also got a smaller one than the one for this truck cause the one for this truck was maybe 1/4 inch from the hood. Sketchy as hell. Patina is staying just the way it is I love it. I painted the wheels back to the gray color and I was gonna clean up the paint since it's really dirty and I think it'll look awesome. I've been looking for one of those distributors already cause the dual points one had us scratching our heads and I don't like the points system myself. Distributor is tuned in check did that yesterday and it didn't change the problem. Did it the exact same way before and after completely re-setting the ignition timing. Point gap is at .018 if I remember correctly, dwell angle is at 52 degrees and timing is at 12 degrees before top dead center. I live at 7600 altitude hence the 12 degree timing. It started to run a whole hell of a lot better overall but still has the stalling problem. Fuel pump is not the original one, I have the original one still so I'll give it a look. That's an O'reillys fuel pump and was the first part I installed on this. I'll compare with the old one but I don't remember a spacer on either one cause I would've noticed that. The original one wouldn't pump hardly anything even after blowing it out.

[banzai510(hainz)]

there is a spacer between the fuel pump and the head surface  stock one is black and the aftermarket is usually white.

uses 2 gaskets, 1  on each side

 

the dual points I usually just use tha main one. the one with the bigger condnsore and I pull the 2nd wire off.  I could never get them right. ,anyway they only work in like 3rd gear anyways on the 2nd set ( at least the 510s)

 

looks like this

https://www.ebay.com/itm/184564333339?hash=item2af8e43b1b:g:HC0AAOSwyCpfyQVF&amdata=enc%3AAQAIAAAA0FvvJYRXk0dL5FQxtxxU%2BevbadlxqDjdkXZNaTesIJoeBu7NR86JakzQLsh7IN5px3FZ%2FkR3oYv%2F5YgzV4JMod37kBWqq7zuyCFPvwuJWDZ3Aw841brv0t0UxRQL2xIh%2F97N8G2BXRxhQe9HWQmhWiKyZtrb62noiq0YFGO%2FM6xzxwWf8%2BJdmhj0Z8T%2BO%2BHGS6VJAWb9NgeKc8F6kMDW%2BRUli7k2KGQzQ1z34z77aaILlGTMkriq4wqdjbEtA3zMhebVs78VONOYWuqrD%2BvrCkY%3D|tkp%3ABk9SR9aFwrXGYg

Edited August 26, 2023 by banzai510(hainz)

[Driver915]

Just checked and yes the fuel pump has it's spacer. Now to find that flow guide valve and hook it back up. Pictures of spacer and my battery tie down. It isn't perfect but the original tie down was gone. The relay and voltage regulator that are unhooked are like that on purpose. The relay is for electric choke which I don't have anymore and was giving me a dead short in my electrical and the voltage regulator we bypassed and put a 1978 model 620 alternator with an integrated one on it. Pretty sure my dad had posted here about that electrical disaster. I capped off the port underneath the carb too. Will get this all fixed then see if it runs any better. Also trying to track down brake wheel cylinders for this truck, is there a way to tell if it has 3/4 or 13/16 cylinders? I see options for both but no clue how to tell which is which.

[banzai510(hainz)]

I would have gone across the other way on that battery strap and fit right in the grove of the filler caps on the battery instead of drilling into the fender

 

I always now try to get the shortest batt cable to the starter if possible so the insulation dont wear thru and short out on the metal.

 

Batt cables that are molded alike better that the Neg you got with the clam shell end will cause issues later. I hate them myself but is what it is.

 

we here in Ratsun to prevent electrical diasasters so dont be in a RUSH!!!!!!!!! tearing apart shit.  yes you got to remove the choke relay to prevent a battery drain. So you must have the 72 like mine. I just put a Manual 32/36 in there and didnt work about the electric choke version. but I run the old 35amp alternator cause the L16 use the smaller ear bolt thru the mount.  Later Car had the beefier bolts and the smaller 35amper holes are to small

 

I would get a cig light volt meter. and use that. I like them.

you can see when you load down at stop light or OVERVOLT  which cooks the battery or really tell the volt reg is bad in your alternator

there are many version but make sure you get 1 that can detect over 15volts.  soem early one only showed GREEN  and you could be over volting the battery

https://www.amazon.com/Battery-Charging-Condition-Alternator-Display/dp/B07422ZPT4/ref=d_bmx_dp_qh6kkxqn_sccl_4_3/139-3681274-6985364?pd_rd_w=RFP47&content-id=amzn1.sym.d7cf88b4-d229-4890-898f-747d13a2098c&pf_rd_p=d7cf88b4-d229-4890-898f-747d13a2098c&pf_rd_r=ANQCN28KTE60EK954YRP&pd_rd_wg=3YpvS&pd_rd_r=3da58122-7b34-4d09-a6a7-2e13caf044e7&pd_rd_i=B07422ZPT4&psc=1

 

 

Edited August 26, 2023 by banzai510(hainz)

[datzenmike]

The one pointing to the back goes to the tank vent line.

 

Top goes to air filter which you don't have. It allows air back into the tank as the gas is used up so it's filtered to keep crap out

of the tank.

 

Bottom goes to the tiny tube on the larger crankcase vent tube.

 

 

Engine off...

Any gas evaporated from hot weather builds slight positive pressure and pushes through the guide valve and into the engine crankcase for storage. It's heavy so will settle above the oil pan

 

Engine running...

Vacuum in the intake draws fumes through the PCV valve that's connected to the crankcase vent tube. The stored fumes are burned by the combustion process. The valve cover is vented to the air filter letting air into the engine to replace that taken out.

As gas level lowers in the tank causing a low pressure, filtered air is sucked into the gas tank to replace it. The gas cap is sealed.

[Driver915]

The reason the battery strap is the way it is was to prevent the battery turning over and welding itself to the head. I saw that happen on a Z and it scared the hell out of me. I didn't wanna drill in the fender either but it seemed to work ok. The reason the negative has the cheap ass terminal is cause the nice one broke off. I was tightening it one day and split it right in half. It was a new cable too. I put the clamshell on it just cause it was there but I wanna get new cables again. Yes it's a 72 model and the battery would drain down to nothing overnight. Chased that for damn close to a month. The alternator I have is a 35 amp too just with an internal regulator and it bolted right up I didn't have an issue with small ears. I swapped to it because the original regulator was dead and the aftermarket one I bought wasn't working either. I'll look into one of those voltmeters but when we were testing we had a volt meter directly on the battery and had it up at high RPM and all and this alternator setup would stop right at 14.6 volts no matter how high you pushed it, the original with a regulator would go up into the 15-16 range. Still check it occasionally and it's been charging fine since we swapped to the newer alternator.

 

 

I got the valve hooked back up just as that diagram shows but where do I hook up the line that's supposed to go to the air filter? Do I need to add a port to the Weber filter or just leave it open or buy a filter to go on the valve? I'm lost there but the rest makes sense now I had it all wrong. Makes me feel better to know more of the original junk is back on it too.

Pictures are what it is now, other than using too big of line to cap off the vacuum port (it's what I had) the rest seems to be hooked up right. Yes I see my brake fluid leak. Brand new master cylinder and the reservoir is leaking all over the place. So guess I need another one. Was a Dorman one that I bought, thought it would last more than 3 weeks and 4 short drives.

[datzenmike]

Better!

[Driver915]

Got all that back together, went for a ride and it drove good for about 20 minutes, then it started dying again. So I guess it wasn't related to the fuel vent system. Instead of just straight up dying this time it just acted like it wasn't getting constant fuel, by how it was running and how the pump works it felt like it was only getting fuel every time that pump got hit by the cam lobe. Holding my foot down on the throttle it was jumping around like crazy. Died when I came to a stop. I gave it a little throttle when cranking and it fired right up and drove back home and into the garage like nothing happened. I re-adjusted the carb after capping off that port and hooking up the valve, tested for leaks and there aren't any vacuum leaks that I can find (spraying a little bit of brake clean near any vacuum ports/hoses listening for it to choke). I just had the ignition set yesterday and haven't touched a thing on it. I doubt it's out of tune. Looked around the carb as much as I can and it looks clean. Suppose I could blow it with compressed air but I don't see any dirt or debris in it. Unless somehow the needle is getting stuck and not letting enough fuel into the bowl. Judging by the way it's been running when it does die I don't see it being ignition related. All the contacts on the points, cap and rotor looked perfect when I had it apart yesterday. I really don't wanna tear down the carburetor but it seems like that's where the problem lies now.

[mainer311]

Guys, I just thought of something. Is there any way that the dual-points/relay/emissions system could be cutting spark somehow? Like, the relays set off the retarded set of points, but it's not hooked up, so it dies, etc.? And then returns to normal operation when the regular advanced set of points is activated again? Just a thought. 

[Driver915]

That could be a problem. I couldn't get the second set of points to come on at all while tuning it. I even checked the plug with a test light revving it and such and got nothing. Then again I have zero idea how that dual points distributor works. I'm wondering if I have a fuel clog somewhere between the pump and carburetor cause the pump is moving fuel but I pulled it off again tonight and it's pretty damn weak compared to when I first bought it (almost weaker than the clogged stock one, it's just barely moving fuel) thus running the bowl dry after awhile of driving. So was gonna tear into that and blow some lines out tomorrow. If you can give me a heads up on how that dual points system is supposed to work and how to mess with it let me know. Or a place to buy a single point/reputable electronic distributor. I'd love to convert it to electronic or single points but according to Mike finding a single point distributor for these isn't very easy, and looking for electronic ones all I can find is eBay stuff and there's stuff I trust off eBay and a distributor isn't on that list.

[thisismatt]

Filter before the pump?  Run it off a can for a while?