521Pickup carb problem??

[Drfixit]

I just bought a 69 Datsun 521 pickup with a 1.3 liter. The symptoms are is acts like its running out of gas when the engine warms up. If you spray starting fluid into the carb you can keep it running but when the spray stops so does the engine. Float level is great as is fuel pump output. When it dies the longer you let it set the longer it will stay running the next time up to about 5 minutes. When it cools all the way down you can start it right up and all is fine until it warms up then it dies acting like it ran out of gas although you can plainly see plenty of fuel in the carb window. Think its the carb? Buy a rebuild or spring for a Weber? One thing I havent checked yet is the gas tank vent but its late and willhave to wait till after work tomorrow.

 

Thanks in advance,

 

Mark

[datzenmike]

Just loosen the gas cap and try, doubt that's it. One thing that shuts off when warm is the choke. Perhaps the primary jet is partially plugged and as long as the choke is on it enriches it enough to run.

[Drfixit]

Of course it would have been too easy of it was the tank vent. Its a manual choke and it doesnt matter what position its in it still acts the same.When it starts to die out closing the choke doesnt help at all. As long as the window is full of gas the truck should continue to run right? I wonder what the heck being warm or maybe just running for that length of time has to do with it..........

[Nicholas7620]

Try removing the carburetor, clean up the manifold area and put in new mounting gaskets. My Datsun needed new mounting gaskets after 20 years there is significant leakage and sludge and varnish. A freshly rebuilt carb, new gas filter should cure your problem.

[ariascarlos1990]

Check your fuel pump. Take off the fuel line and crank the engine over (dont crank it for to long or you will have gas everywhere)

[Drfixit]

I removed the gas line from the carb and put it in a can and had the old lady crank the engine. Didnt get a steady stream kind of hit and miss. But if theres plenty od gas visible in the window shouldnt the truck run? Fuel pump just keeps the bowl full doesnt it?

[datzenmike]

Well he did say:

 

Float level is great as is fuel pump output.

 

Mark

 

A full carb may still have a vacuum leak or blockage. Odd that when cool the engine runs and quits when warm.

Edited November 14, 2008 by datzenmike

[Nicholas7620]

I guess you need a new, or freshly rebuilt carb or very clean old carburetor to rule out a bad carburetor.

 

 

My engine in my 1976 Datsun B210 is doing the same thing. When cold the engine runs great, of course the choke is on. After I drove for a while and the engine warmed up, there was no ability of my engine to idle at stop signs, red lights or bumper to bumper traffic. :eek::eek:

 

I took out my carburetor and sent it back to Recarbco in Pittsburg, CA for a check up because my carburetor was still under warranty. Right now, I'm removing, disassembling and cleaning my smog emission equipment.

 

Happy wrenching :)

[Drfixit]

Well I am fairly sure its something in the carb. Tomorrow I will tear it down and clean it all up and see what I can find. Thanks for all the help

[Drfixit]

One last thought, the problem I am having is I bought the truck from a kid.....well anyone under 30 is a kid to me LOL He claimed to have installed all kinds of new stuff which when I finally got to looking at it after I got half way home and then called a tow! He had no air filter on it, no pvc or EGR and claims to have put a new carb on it. I'll bet he didnt spring for a new gasket!! I cant complain I love the truck and will love it a lot more when it runs LOL.

 

Mark

[datzenmike]

Might not even be the stock carb .. got a picture of it. As for rebuilding, sometimes just cleaning is enough.

[Drfixit]

Heres pics of the carb. BTW there is a label under the hood (See photo) that states this vehicle is equipped with a fuel cut off device. I cant find it in the Haynes manual what info can you give me.

 

Thanks a bunch

 

Mark

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Edited November 16, 2008 by Drfixit
add pic

[datzenmike]

Can't read it... does it say " fuel tank is equipped with a fuel cut off..." if so it may just be a valve in the tank that closes in the event of a roll over. The carb is a really old L type. May not have had EGR there is no carb outlet for it only vacuum advance. Really needs PCV though.

Edited November 16, 2008 by datzenmike

[Drfixit]

The label reads

 

"This car is equiped with a fuel cut off"

Regular service is required to maintain low emission standards"

 

Then it gives idle at 700 rpm and timing figures. The pvc valve is screwed into a tapped hole in the intake manifold just below the carb and is attached to a metal tube I am assuming is the crankcase vent. The hose that connects these two was bad and leaking and it is different sizes at each end ??? Cant find another one so i am going to have to build something with reducers. My 55 chevy with small block had pvc taken out and crank and valve covers vented to the atmosphere, no good with J13?

 

Thanks again,

Mark

[datzenmike]

Yes the hose has different size ends. Best to run a PCV valve. It uses a small amount of manifold vacuum to draw out unburnt fuel and water vapors which are found in all engine crank cases. If left they condense and mix with and dilute the oil. This means you have to change it sooner. My dad had a '51 Chev and in '64 our neighbor pulled the pan to replace the mains. Engines prior to '53? didn't have oil pumps or filters. Or PCV valves... in the bottom of the oil pan was over a half inch of white/gray 'paste', water/gas that had condensed and settled to the bottom. I always wondered why it didn't take 4 quarts to fill at oil change time.

 

The PCV valve wasn't in use much before the early '60s. Your '55 had a transplant??

[Drfixit]

It had a 283 bored to 292. The PCV went to a intake tap just under the high rise Edelbrock The valve cover didnt have a breather and the oil fill tube on the front of the intake was of the sealed variety. I figured all this out when I got on it real hard the first time and bleww the dipstick out of the tube and rained oil all over the engine LOL. I've been searching but there doesnt seem to be as much on the J13 as you could find on my old Toyota 22R. All I want is a good running engine but its always been fun to tinker with aftermarket stuff. Thanks

 

Yeah the old oil filler tube at the front should be open on them. The valve covers are sealed and blow by would build up. I had a more or less stock 283 4bbl Holey with Corvette Aluminum close ratio 4 spd in my '55. Those were the days, eh?

 

edit: That was my '57 instead. My '55 had the Blue Flame six.:D

Edited November 16, 2008 by datzenmike

[Drfixit]

Well I pulled the carb and blew it all out with carb cleaner etc. Found one vacuum leak that I myself had caused so i fixed that and it starts and runs great..........when cold

as soon as it warms up it acts like its starving for gas with or without the choke on. Tried tightening the intake manifold which was a little loose but nothing major and no change. The engine didnt have a thermostat in it when I got it and I put one in of course I wonder if the seller took it out to keep it from warming up thus stop running? I dont know what else to check besides replacing the carb.....any ideas?

[Drfixit]

Well of course I cant just sit here so Ive been back and forth messing with it. 2 schools of thought. The seller replaced the coil (He says) and the fuel pump. The fuel line from the tank ran over the top of the valve cover to the fuel pump then along the head by the distributor to the carb. Vapor lock??? I read another post where a guy had a wire that would short out to ground when hot and be ok when cold so........I moved the fuel line and jiggled and cleaned and moved all the wiring from the coil and resistor to the distributor and now it seems to be running ok??????????????? I ran it in the garage for 2-3 times longer than it normally runs and it got good and up to temp and everything. Scared to drive test it dont want to be stuck down the block. Guess I will wait till daylight when the wifes off and she can follow me. Sure glad I didnt buy a new carb!!

[impala_631]

it might be vapor locking,the intake is mounted to the exhaust right?

[kelowg]

did you remove the two cap screws near bottom of carb, the one at an angle. they're on the underside of what i would call jets. this very common on these carbs

[Drfixit]

Yes I took the plugs and idlre screw out and blew every jet and orfice I could find with carb cleaner. Now the problem has seem to have taken a turn. I can drive it ok, it idles ok but right off idle it acts like its starved for gas. It sptutters, spits missis then if I pump the accelerator peddle a little and get the revs up a touch it takes off and is fine in mid range. It now seems to be the first 1/2" of peddle where it has problems. I checked the points and plugs and found the vacuum advance is not working at all! I was going to check the timing but I cannot find the reference mark on the pulley thats where a harmonic balancer is on a chevy. Can someone send me a pic or describe exactly where the mark is that you line up with the pointer? Theres no picture in the Haynes manual. Do you think lack of vacuum advance could be part of the problem? I had a 68 Dodge Charger 440 and I put a new dist in with n vacuum advance and the off idle acceleration suffered.

 

Thanks in Advance

 

Mark

Edited November 22, 2008 by Drfixit
spelling

[datzenmike]

Take the distributor cap off so you can see if it advances. Take the hose off the carb and suck on the end... the distributor should twist clock wise. Pinch the hose and it should hold the advance... if not there is a leak, maybe in the hose.

 

The timing notch should be on the back rim of the rear pulley. Set the motor near BeforeTDC then look/feel for it near the timing plate.

[Drfixit]

The vacuum advance tries to work I guess its probably just all gummed up. Suction tries to move the plate but it wond hardly move by hand. I found four marks on the pulley but cannot read the markings. I have a pointer on the engine that reads 0 - 10-20 I would imagine that is in degrees btdc. I cant get a decent photo of the pulley marks. I adjusted the timing by the seat of my pants and either fully advanced or retarded made no difference in the way the truck runs.well full retarded doesnt idle too good but it didnt effect the problem I now am back to thinking its the carb. I guess instead of buying a new same ole oem carb I might as well get a weber........which one?

[Drfixit]

Well got it all fixed up. Replaced the carb with a weber 32/36 and it runs great. I thought it was probably the carb but it was such a strange ass problem that changed a couple of times as far as symptoms were concerned. Thanks alot for all the help

 

Mark

[impala_631]

it seems too me that the j13carbs are nothing but trouble:mad: