tbi problems

[mmeiers85]

I just picked up another truck, it's a 92 with the tbi 350. I am having a variety of problems. I have done tons of research but was hoping someone could give me some more suggestions because I am at a loss.

It starts then dies quickly. If I blip the throttle I can keep it going, eventually it will idle high (cold) like it should and I can shift into D/R and move the truck around. Once it starts to warm up, it will gradually idle down lower and lower until it dies. Sometimes it will catch itself and idle up but always dies eventually.

It also has lots of hesitation while driving.

I tried spraying carb cleaner into the TB as it was dying to check for a vacuum leak but it just dies or bogs down.

I replaced the cts, distributor/wires are new according to PO. I checked the tps, it reads .40v at idle and gradually goes up to 3v at WOT. I also checked the 4 wires on the iac, ABCD voltage reads .91, 12, 12, .91 respectively.

The injectors spray great, it looks like it had been recently rebuilt. Fuel filter looks new.

Any ideas? Check timing? Are the iac/tps numbers right? Could the fuel pump be failing and losing pressure as it gets warm or something? Any ideas are appreciated!

 

[Thatlowchevy]

i would check timing, my '95 was doing this today then i checked the distributor bolt and it has loosened just a bit so it rotated the timing by 24*. such a small thing can be a huge headache!

 

[mmeiers85]

Ok I will check the timing tomorrow, isn't there some electrical connector I have to unhook to set base timing?

 

[90halfton]

I just picked up another truck, it's a 92 with the tbi 350. I am having a variety of problems. I have done tons of research but was hoping someone could give me some more suggestions because I am at a loss.

It starts then dies quickly. If I blip the throttle I can keep it going, eventually it will idle high (cold) like it should and I can shift into D/R and move the truck around. Once it starts to warm up, it will gradually idle down lower and lower until it dies. Sometimes it will catch itself and idle up but always dies eventually.

It also has lots of hesitation while driving.

I tried spraying carb cleaner into the TB as it was dying to check for a vacuum leak but it just dies or bogs down.

I replaced the cts, distributor/wires are new according to PO. I checked the tps, it reads .40v at idle and gradually goes up to 3v at WOT. I also checked the 4 wires on the iac, ABCD voltage reads .91, 12, 12, .91 respectively.

The injectors spray great, it looks like it had been recently rebuilt. Fuel filter looks new.

Any ideas? Check timing? Are the iac/tps numbers right? Could the fuel pump be failing and losing pressure as it gets warm or something? Any ideas are appreciated!

Checking fuel pressure wouldn't be a terrible idea

 

[90halfton]

Ok I will check the timing tomorrow, isn't there some electrical connector I have to unhook to set base timing?

Yes. Electronic advance has a connector under the plastic cover on passenger side firewall. I believe it's a brown wire. Could be wrong though. Unplug it and set timing to 0. Will have to unplug battery after to get dummy light to go off.

 

[TylerZ281500]

check fuel pressure, stock they are anywhere from 9-13 psi usually you want to stick around 12 if you decide to bump it, carb cleaner is poor for vacuum leaks use propane,

base time to 0* you dont need anything more, with the esc unplugged, brown wire in engine bar. if you have a problem check your codes, jump a and b terminal on your aldl.

 

[mmeiers85]

Ok. If fuel pressure is low do I need to think about replacing the fuel pump? The computer hasn't thrown any codes yet.

 

[90halfton]

Ok. If fuel pressure is low do I need to think about replacing the fuel pump? The computer hasn't thrown any codes yet.

If psi is low its either fuel pump, filter, or plugged up fuel line. If psi is intermittent verify its getting constant power and there's not a connection or ground issue.

 

[Jrgunn5150]

check fuel pressure, stock they are anywhere from 9-13 psi usually you want to stick around 12 if you decide to bump it, carb cleaner is poor for vacuum leaks use propane,

base time to 0* you dont need anything more, with the esc unplugged, brown wire in engine bar. if you have a problem check your codes, jump a and b terminal on your aldl.

I've seen this posted several times, why is advancing the base timing not recommended on TBI trucks?

 

[90halfton]

I've seen this posted several times, why is advancing the base timing not recommended on TBI trucks?

Can set it a couple degrees advanced but dosent have any noticeable positive effect. Electronic advance takes care of it. That is as technical as I know lol.