My truck is driving me CRAZY: Dead in the water

[metalmonkey47]

I feel like every few months, I come across some stupid problem that ends up in a thread like this, and I can't seem to find a solution until someone points me in an unexpected direction. 

 

My truck is currently un-drivable and has been for 48 hours now. No bueno.

 

LZ22 W/ about 5000 miles

blah blah

38/38 Weber

Matchbox dizzy

etc..

 

Driving it in an all out downpour, came under a bridge and it started to stutter. Came out the other side and it fell flat on it's face. No idle, no throttle, etc. Just dead. I pulled the carb apart on the side of the road and fought with the jets looking for a clog of some sort. Opened the carb and the bowl was full. Pulled both primaries and found nothing. Same with the idle jets. Put it back in and started it and it ran okay for a second, revved fine, then choked and died. We managed to get her going just well enough to get it down the road to Master_o_turbonics who built to motor. The whole drive it ran like piss, refused to idle, and I had to drive it at nearly full throttle pumping the throttle at lights to keep it running at lights. The more load on the motor, worse it ran.

 

Got it there, and for some reason we can't figure out, it ran just fine. No problemo. We even managed a squirrely burnout in the parking lot. I left and headed home and it ran 'okay' but seemed to be lacking in power.... it also struggled to idle at lights.

 

I've had issues with this adapted getting the carb to seal because of a crack on the adapter near on the threads for the stud, but remedied that by packing some JB weld on the outside of the adapter, and JB welding the stud in place so it didn't slip on the garbage threads. 

 

When I got it home I found that the stud on the corner was a little loose, and I checked for vacuum leaks around the carb with some carb cleaner and strangly found nothing. I went ahead and made a new gasket for the base, and fixed the stud again to get it nice and tight hoping it was just a fluke vacuum leak but that wasn't the case. Now I have little to no idle, and no power under load. Revs 'okay' at best. 

 

 

Seems like the issue has to be carb related. Or at least, acts like it's starving for fuel...but I'm no expert. 

 

 

ironic, because I was actually driving to see m_o_t to buy a set of Z car SU's when it shitted out. 

[hobbes_the_cat]

Don't overlook the electrical side of things. When it's real wet that the first place I look. Some moisture in the dizzy? matchbox got water in it? Uninsulated wire get wet?

[wayno]

Check the outside of the dist. cap, is it dirty, I had some issues when the rainy season started last year, the outside of the cap was arcing and made low RPMs a bitch, starting when cold was a major hassle also.

Make sure the wires going to the dist. are also tight for the IE, they sometimes get loose and act up.

[metalmonkey47]

Totally overlooked the dizzy. I'm gonna pop the cap tomorrow morning and see how it looks. I didn't notice anything when I was working on the carb, but maybe it's not tight and got some water inside. It was raining like hell after all.

[devilsbullet]

check plug wires too. I had close to this problem, thought it was all carb, 300 bucks and a new weber later, realized my plug wires were shit...

[cruznude]

Yea most definitely check the electrical.  I had similar problem and thought the carb wasn't getting fuel because the lack of power, and after changing out filter,draining all the gas and putting new in.  Come to find out it was a small fracture crack on the cap.  Who woulda thought.

[datzenmike]

This is easy and explainable. Driving in the wet. Wet air filter will restrict it and choke it too.

 

 

Get a pair of Nitrile surgical gloves. EMS and Dr. offices have millions of them, they give them away. Don't get latex rubber they dissolve in a few weeks. Nitrile will last the winter. They are chemical resistant and gas won't dissolve them. Poke a small hole in the finger and thumb tips, remove nipples, and carefully push the wires through. Connect back up. Roll the glove up like a condom. (if unfamiliar with them ask your mom) slip over dizzy and roll down to cover the cap. Make the hole small so the glove makes a tight seal around the wires.

[The Dat-side]

Sounds pretty similar to what just a happened to me. One of the wires on the matchbox was barely held together by a few strands of wire.

[datsundna]

Totally overlooked the dizzy. I'm gonna pop the cap tomorrow morning and see how it looks. I didn't notice anything when I was working on the carb, but maybe it's not tight and got some water inside. It was raining like hell after all.

I'm sorry but 48 hours of no vehicle and this major problem and you didn't look at the dizzy?  This is probably the most moisture sensitive part on your entire truck.

[datsundna]

This is easy and explainable. Driving in the wet. Wet air filter will restrict it and choke it too.

 

 

Get a pair of Nitrile surgical gloves. EMS and Dr. offices have millions of them, they give them away. Don't get latex rubber they dissolve in a few weeks. Nitrile will last the winter. They are chemical resistant and gas won't dissolve them. Poke a small hole in the finger and thumb tips, remove nipples, and carefully push the wires through. Connect back up. Roll the glove up like a condom. (if unfamiliar with them ask your mom) slip over dizzy and roll down to cover the cap. Make the hole small so the glove makes a tight seal around the wires.

this is an oem option,   not as tight as a glove but might not look so rigged either. 

http://www.ebay.com/itm/NISSAN-D21-240SX-KA24E-DISTRIBUTOR-COVER-RUBBER-s13-OEM-sparkplug-wire-/181208188330

 

[q-tip]

No checking dizzy is no bueno.....remember Fuel. Spark. Compression. These are the bare necessities of the internal combustion engine....

[banzai510(hainz)]

when wet or lot of moisture in air. alwasy go for the dizzy. Why you picked the carb?

carb only if you think the gas tank has a leak and water getting inside.

[datsunaholic]

Also I agree, probably got the dist wet.   Most of my popping/backfiring/running like crap after hitting a puddle was because water got in the cap and it was just randomly arcing in there.  I carry paper towels, I've had to mop out the cap more than once.

 

On the fuel side, there are a lot of ways of getting water in the tank.  620s have the vapor tank in the wheelwell, and once it rusts a hole in it, the water spray off the tires ends up draining straight into the gas tank.  I had one that was more than a little rusty:

 

 

 

By the time I'd gotten all the rust and moisture out of the fuel system, the truck had rusted apart anyway.

[K_trip]

- removed -

[metalmonkey47]

No bueno on the dizzy. I played with it a bit and it's fuel starvation. I have a clear filter under the hood. Noticed it's not filling up past 1/4 full. It's new, I also have one back at the tank. It's about 6 months old. (until tonight that is.)

 

I'm going to get a fuel pressure tester and a new filter at the back and check the pump up front.

 

 

Gonna get a few feet of fuel line and drop it from the pump into a can of gas and see how that goes first. 

[banzai510(hainz)]

if your carb has gas  it shoud at least idle cause it uses very little gas.

 

since you had carb apart already. ck for tiny rocks in the jets????

 

you pull the out put of fuel pump and see if squirts???????? if yes then the delivery is good.

 

I run 2 filters on my truck and they are never full persay.

 

 

 

Maybe it only neede the dizzy dried out then you induced another proplem by ripping it all apart. To me it would have been dizzy related soon as it happend

[q-tip]

Listen to the master of the L.....he isn't titled L motor god fer nothin

[metalmonkey47]

Sorry guys, I was in a rush earlier and didn't get to type much.

 

 

I did originally check the dizzy and there were no obvious signs of moisture so I skipped it. Seems to me the issue would be more consistent. Lets follow the series of events:

 

-Broke down, truck wouldn't idle and had no power under load suddenly. No advanced warnings.

  -Checked jets, vacuum leaks, etc whatever I could on the side of the road. Still had spark so skipped that process.

-Got it limped to Master-O-turbonics shop. Missfiring, wouldn't idle, ran like it was on two cylinders, but if I pumped the throttle or drove hard it seemed to settle out.

  -Got there and it seemed to be running fine at that point. Slight hesitation, but it still ran better and almost normal.

-Left the shop and it ran good all the way home, except it didn't seem to idle consistently. 

-Got it home.

  -Popped the dizzy cap and took a quick glance. Nothing. No signs of carbon tracking, looked fine.

  -Cleared out all the passages with compressed air/carb cleaner. 

  -Looked for vacuum leaks, found none, but found carb stud was loose. Made a new gasket and fixed the stud/crack.

 

Now today.... Seems like I was able to get the thing to idle after a short time warming it up. The idle would jump up and down, until it was up to operating temps and it was fairly consistent from there. Tried to drive it, but under load it stalled again, and stopped idling. 

 

The reason I'm still focused on carb/fuel delivery is because when it's warm and idling strange, I can close the choke slightly and it will stabilize. Also, when it starts to stall, if I grab the throttle and pump it a bit, the extra gas from the accelerator pump seems to steady it out and it revs just FINE...

 

Also seems pretty strange to me that the fuel filter under the hood is only getting about 1/4 full. Seems like it should have a LOT more in it then that. Hence why I'm wanting to focus on fuel delivery... It's very possible something else came about when I pulled it all apart. I have not checked the pump yet. I'm going to get a pressure tester from work and just measure it out. Should be simple. 

 

But, you guys are the experts here. I'm just here to learn so suggest away, I'm willing to investigate anything. I'll pull the dizzy tomorrow morning before work an see how she looks again. Got some WD-40 on hand.

[zed]

my fuel filters run about half full mostly. How old are your plug wires?

[EricJB]

I had a fuel problem with my 521 (L16/ weber dgv) many years ago. Every time it rained, it ran like shit, if at all. I found that some fuel filters would not let water through. If they got wet, they were plugged. And they didn't recover from it. The vent hose on the gas tank was split, and when I drove it in the rain the back tire would sling water at it.

 

Remember that water is heavier than gas. If you drain the filter ( or gas tank, or carb bowl ) it will look like a bubble at the bottom of the pan.

[metalmonkey47]

PLug wires are pretty recent. Probably about 6 months. I used my timing light to check from misses in the spark while it was running bad, and it was consistent, so I'm just gonna rule out spark.

 

 

NOW this morning alone, I've pretty confidently figured out and decided that it has to be fuel pump related. I disconnected my underhood filter and ran it into a gas can to watch the fuel flow, and the filter stayed consistently low. Barely any fuel touching the media. photo::

 

 

 

Now with that said, the pump can't seem to keep up. WIth the truck running, when it starts to stall/run rough it looks like this:

 

 

So if there's no fuel in the media, how the hell is any getting to the carb is my question? 

 

For shits and giggles, I ran fuel line straight to the pump to bypass the filter on the off chance maybe there was something physically wrong inside the media that I couldn't see. No change in running. Still misses when revved, and idles like shit unless we choke it.

 

 

 

 

Soooo I've ordered a fuel pump, I'll have it by the end of the day.

[datzenmike]

You haven't proven the pump is bad yet.

 

 

Pull the hose off the carb and direct into a pail and crank. Fuel gush out?

 

If yes the pump and filter are good. Problem is carb related.

 

If no gas.... feed gas to the pump from a bottle and crank. Fuel gush out?

 

Yes...Could be filter or the fuel line plugged.

No.. pump is probably no good.

[banzai510(hainz)]

My post #16 ,you pull the out put of fuel pump and see if squirts???????? if yes then the delivery is good.

 

START WITH THIS 1ST!!!!!!!!!!!

 

as mike said also ck the out put of pump.

 

I had a pump look bad once as I cked the output and nothing came out. Find out the input hose of the manual fuel pump had a slightly crack in it and was sucking more air than gas thus making it seem like it was running out of gas.

SO CK IF CLAMPS TIGHT!!!!!!!!!!!

 

 

But like I said at idle tha motor doesn not need alot of gas. if the float bowl is full. You can see gas squirting out from the accell pump. If bowl was empty then you would not be able to run at all.

 

if you have to choker it than either you have a cracked carb spacer or your idle jet is plugged. or possible a main jet and when you run the choke your putting more gas thru the 2nd main jet to get it to run.

 

But cking the output of the fuel pump is EZ and you didnt say if you did it.

Now you dissambled the carb so it could be soemthing you induced

[q-tip]

I have an electric fuel pump in my 620 and the filter has that little fuel it in and the truck runs fine.

 

It is for certain a fuel issue of some kind. Try running some fresh fuel straight out of a has can thru the fuel pump bypassing the filter. It could be water in your fuel....

[EricJB]

Not uncommon for a filter to have air in it. When it is full, it is usually dirty. I had a fuel pump die once when I was really broke. Buying a new one was not an option. I pulled the top off and found the check valves had some crap in them. Cleaned it up and it ran fine.  

 

Putting gas dryer (heet) or ethanol mixed, or oxygenated gas can loosen shit up in the tank. Then your chasing your tail. Best to pull the plug.