acousticeroticah

I am currently working on a 91 toyota pickup v6 4wd ext. cab. I have been a long time reader to this forum, but first time poster. this truck has set for about 18 mouths due to body rust that wouldn't pass inspection. before it was parked there was a new (40,000 mile) engine put in the truck and friend assures me it had no problems. upon first inspection I realized the fuel pump was not working. changed the fuel pump, cleaned the tank out, and cleared old gas from lines. still not start. next a pulled the rotor, cap, button, wires, and new plugs. still not start without gas in the intake. when it would start it seemed to run very well until the fuel was gone. next I took the injectors off replaced ones that didn't have resistance and cleaned them all over night. at the same time I cleaned the crossover intake, efi in the intake, and the IAV in the throttle body. once i put it all back it still didn't start. tried gas in the intake again and it would start and seemed to run pass the point of the intake gas, but I would have to try to keep it going and it would backfire through the intake. I hate to give up on vehicles, but this one has me scratching my head wondering if this will be the one I may not figure out. any suggestions will be tried.....can't give up on a one owner toyota

Cyberman

You need to make sure you've got a working system. It sounds like you're not getting fuel to the engine. Did you replace the fuel filter? Also, check the fuel pressure, following the FSM.

AW1090

I'd check around the fuel pump again. Make sure you don't have a block anywhere and that there is pressure on the preside of the fuel filter. I know this sounds a little dumb, but it's a great way to isolate the problem. I had to drop the fuel tank to replace the fuel pump on mine and later found out that when replacing the tank I pinched a small 6 in portion of the fuel line that comes right off the top of the tank. This kept my truck dead for months. It ran great after I straightened out the kink. I wouldn't have found it unless I took a look at the rate of fuel coming out pre fuel filter.

acousticeroticah

have checked the fuel pressure to the fuel delivery pipe. seems to be plenty of pressure. I didn't have a fuel psi gauge but there is enough pressure to send a stream up past the open top part of the hood. will be borrowing a gauge and check exact psi, but not believing this is the problem. fuel filter is new by the way. one issue I think it may be is there are three lines coming from the tank. one is a large main supply, then there are two smaller lines. one a return and the other a supply. I believe these lines may be crossed, if so could that cause this problem. Also a old racing buddy of mine seems to believe that it is the timing. although my attempts at adjusting the timing at the distributor have not seemed to result in any difference in starting or running abilities......don't worry everything was marked and has returned to the original as far as the timing goes.

scope103

You're wasting your time (timing). A timing light is $20; the best you can hope for by "timing by ear" is to blow a hole in a piston. Get a timing light, and set it. You'll need it in the future anyway.

Since it would "run very well until the fuel was gone" with gas in the intake, I have to ask if you have all of the induction tubes (throttle body through the air filter) connected? Truck won't run without them.

If you have a problem in the VAF/COR circuit, the fuel pump won't run once you release the key. Use the FP--B+ jumper to force the pump to run. If that clears up the problem, it's in the VAF/COR.

acousticeroticah

I used a timing light to set the timing back. I only adjusted it cause I have had previous Toyota trucks that required some advancement after a engine rebuild. I do to agree that i was wasting my time with the timing. all of the air/vacuum components between the TB and the air box are connected. I have to ask though what does VAF/COR stand for. I can say that I have listened for vacuum leaks throughout the motor while it was running and I wasn't able to hear anything using a stethoscope.

Cyberman

VAF(M)= Volume air Flow (Meter)
COR=Circuit Opening Relay

Go back to basics: Air, Fuel, Spark, and Compression. Make sure all of the systems work. Obviously, one of them isn't.

AW1090

2nd the CO relay

acousticeroticah

i have checked the CO relay, VAF, cold start injector, coil, and igniter. sadly there is not new change for the vehicle. I recleaned the throttle body and it seemed to help a little bit at first, but not really at all. I removed the spark plugs and have found that I have a black carbon on all of them except cylinder 6. cylinder 6 was wet but still looked new like it wasn't burning. although, all of the spark plugs where getting a pretty good fire when I was checking them. any ideas would greatly help.....I'll keep the info coming to help others

acousticeroticah

after countless checks of every electronic device on the truck I have discovered the problem. turns out that the intake gasket had cracked at some point and was the problem.