DudeZX

Hey guys, I'm new to YotaTech and these trucks in general. I've searched all over and can't seem to find an answer to a problem I'm having.

I recently picked up a 1988 Toyota pickup that needed a head gasket, timing set, and a few other things. I got it all put back together and sometimes it will start, run for a few seconds, then die. Sometimes I can keep it running (extremely roughly) by using the throttle, and I did have it running somewhat on starter fluid, and it would rev out smoothly then. That should throw up a red flag that I have a fuel issue, but everything I have tested seems alright.
I've double checked the mechanical timing and distributor position, checked for power at the injector plugs and tested the injectors themselves. I've turned the distributor and watched them shoot fuel out and have used a 9v battery to keep them open because I thought maybe they were clogged. The fuel pump is working and I have used the diagnostic box under the hood to jump the circuit, even though my Circuit Opening Relay seems to be working just fine, I can hear it clicking and I have taken it apart to make sure. I have tested the fuel pressure and it checks out good at 40psi. I have tested the AFM and manually opened the flapper to power the fuel pump.
My initial thought was that maybe the gas was bad from the truck sitting, so I siphoned all of it out and put in a few fresh gallons.
Spark and compression seem fine as well. I'm usually not one to throw in the towel on an issue, but this one has me stumped. At this point, I'm thinking the ECU has some sort of fault. I took the casing apart and visually inspected it, and everything looked fine.

Any help is greatly appreciated. Also, if there is anyone in the middle TN area that would be willing to come check it out or knows someone I can take the truck to, let me know.

Kiroshu

Hmm..

Fuel pressure tested cold...?

Possible fuel pump overheating from deteriorated fuel left in tank over time...?

Check fuel pressure after engine has run a while...?

Possible computer malfunction....?

Intake manifold leaks...?

Intake air hose leaks...?

Exhaust system restrictions...?

Coolant temperature sensor...?

Cold start time switch...?

Cold start injector...?

DudeZX

The fuel pressure was tested cold. I haven't really had the engine warm or running for very long. I don't like keeping the engine running with the throttle because I have to hold it at what sounds like 3000-3500rpm and it misses terribly the whole time.
I have inspected the intake pipe and it looks fine, all the intake manifold gaskets are new, I inspected all the vacuum hoses and have them hooked up. I can't even hear a significant vacuum leak with the engine running.
I have thought about exhaust restrictions but I haven't gone as far as taking it apart. When I had the engine running at first, it was blowing out clouds of black/gray smoke that I assumed was burn-off from the truck sitting. I ran the engine until the smoke cleared and the engine never ran any better.
I have not checked the coolant temp sensor. I assume it is the type that controls the air/fuel mixture according to coolant temp?
The cold start injector does work, I figure that is what the engine is running on for the first few seconds. I have not checked the time switch.

pcola

any codes?
maybe knock sensor wire... or tps i also have an 88 with a 22re and my tps was sticking causing the same kinda problem or if u removed it while rebuilding it could be out of spec. also egr/ egr ports clogged... i removed mine due to carbon build up
hope any of this might help! and welcome to yotatech and ether way id love to hear what u find. goof luck man

Scrussanation

Yea a bad igniter would throw code 14 did similar things as well as others but mine was a 3vze. Jumper and get some codes

DudeZX

No codes, just the constant single flash. The results may be compromised due to the battery being dead? I didn't touch the TPS during the process and the EGR did not look to be extremely gummed up. I cleaned it off anyways before putting it back together.

DudeZX

I re-checked all vacuum lines today, only had one hooked up incorrectly. I left the coil wire undone by accident while doing some more diagnostics, then pulled the plugs out of curiosity and found they had all fouled, which makes things even more interesting. The truck will hardly ever start now, it usually just cranks and tries to fire. The only times I can get it to run is with starter fluid or holding the throttle open at the right time. I sprayed over the intake and vacuum lines with starter fluid and noticed no change. I suppose I'll check the compression with a guage tomorrow, even though I can hear the compression when turning the engine over. I checked for spark again as well and I am getting spark, but perhaps it is not as powerful as it needs to be to ignite the gasoline, but it will ignite the starter fluid because it is more flammable? In that case I would be looking at a coil or an ignitor, correct?

Kiroshu

Coolant temperature signal is a very significant data factor to the computer for proper engine performance and operation.

Coolant temperature sensor and cold start time switch connecters mix/matched...? Remember they are right be side each other and can be crossed to cause a very similar problem. They are color coded but the connectors are the same.

Faulty Air flow meter...?

Valve clearance...?

^--compression...?

DudeZX

Tested the compression today with a guage and it is all good. I tested the AFM with my meter a few days ago and it checked out fine. The valves are all adjusted within spec. I'm really quite stumped lol.

DudeZX

I was just messing with the truck again, and it would not start until I hooked up the jumper and let the pump prime. It started, idled for a few moments, then died again. I'm thinking the pump is able to produce pressure, but cannot keep up with the volume needed after the engine begins to run. I'm going to throw a fuel pump at it and see what it will do. I have already replaced the fuel filter.

Scrussanation

Instead of throwing parts at it why not do a fuel pressure test that'll let you know for sure

DudeZX

I've done a fuel pressure test, but that didn't tell me the volume of fuel that is being delivered.

Kiroshu

Air flow meter air door(fuel pump engine running switch)... sticky/faulty...?

Fuel pump malfunction is possible.

Opening Circuit(Fuel pump) Relay...?

DudeZX

The AFM is working smooth as silk. I have yet to pull the tank and visually inspect the pump. I am going to plumb in a spare walbro 255 I have for testing purposes and see what that does. I will re-check the COR as well.

DudeZX

Tried a a different fuel pump with no significant gains. Unplugged the cold start injector and the truck will not start at all.

Kiroshu

Check wiring harness running from igniter/coil assembly to fuel injector harness(intake manifold area) for damage and breaks.

Sounds like an injector signal malfunction.

Check Cold start time switch and Coolant temperature sensors for crossed connectors(they are located side by side to each other).

Do you have a suitable vacuum gauge to check engine health and for exhaust restrictions...?

Are you 100% positive on Timing set-up...?

Timing chain installed correctly..?

DudeZX

The harness has a break in the outer insulation right around the exhaust shield, but the wiring itself looks fine. I have voltage at both terminals on the injector connector, but neither of them have continuity to the ground on the intake manifold?
Timing is 100% correct, the truck runs great at idle until the cold start fuel runs out. The cold start timer and engine temp sensors are hooked up correctly. I have no vacuum guage but the exhaust is not restricted and the compression and valve work is fine.

DudeZX

I would think that the only culprits left could be the igniter, ecu, or the harness itself. I have no code for the igniter though, does it always throw a code when it goes bad?

osv

this sure does sound like a fuel issue... however, when you say that the wiring inside the harness looks fine, does that mean that you have actually cut the engine harness open? 'cause if you had cut it open, you probably would have seen some disturbing things with corroded connections... in particular, the hacked wiring that ties the injectors all together, contrary to the wiring diagram in the fsm, which shows the injectors wired in pairs... this happens right about the place where the harness turns to go under the manifold.

I wouldn't suggest cutting the harness open yet, because if it's idling to some degree, the injectors must be working to some extent... I wouldn't think that it could be running strictly off of that single cold start injector??

voltmeter testing for wiring integrity won't always show a problem, because if there are just a couple of strands connected, it'll carry the current that the meter puts out, but not carry enough current to fire the injectors.

try running resistance tests on the sensors that have been discussed, the procedure is in the fsm... although i'm not sure that the engine is getting hot enough to complete the tests.

beyond that, there are extensive detailed testing procedures in the fsm, for nearly everything... have you downloaded that yet?

you are doing a great job so far, please keep us posted.

osv

the main harness for the 22re is on the intake side, not the exhaust side... you never did state what engine it is, I just assumed it was a 22re.