87’ 350 tbi hot start issue

[kychevy]

haven’t posted in awhile but have an 87 350 tbi that would start within seconds when warm b4 I rear ended someone last August. Since then, even cold starts might take 10-15 seconds b4 it starts. Problem is once the engine gets hot and turn it off, if I try to start it back it just cranks and cranks. I can wait maybe 5 minutes to start and it will after 10-15 seconds. However, if I shoot a little ether in it it starts right up and I can drive it again. I had a mechanic replace injectors, fuel pressure regulator, ECT sensor, check fuel pressure(11 lbs) and replace map sensor. Engine runs and idles great. Any help greatly appreciated

 

[Edelbrock]

I had a mechanic replace injectors, fuel pressure regulator, ECT sensor, check fuel pressure(11 lbs) and replace map sensor. Engine runs and idles great. Any help greatly appreciated

Were these parts replaced as part of a troubleshooting process, in an attempt to solve the current starting problem?

 

[kychevy]

Were these parts replaced as part of a troubleshooting process, in an attempt to solve the current starting problem?

Yes, this weekend

 

[Edelbrock]

I would not replace any more parts prior to identifying the problem. Throwing parts at it can complicate the diagnostic process. Also, paying a shop to do a diagnostic would be less expensive than all those parts that were replaced.

For diagnosing the issue, lets start with this:

How bad was the damage? Did it damage anything on the engine side of the core support? Any pics?

Also, have you checked the OBD1 codes? Is there a check engine light on?

 

[kychevy]

Haven’t replaced anything so this is how it looked after I hit them. No damage on engine side

 

[Edelbrock]

So the problems started immediately after the impact? Like, you turned the engine off to exchange insurance, and then when you went to restart - the problem was there for the first time?

 

[Edelbrock]

You have a lean condition that is worse when hot. So I would get it hot and then pull the air cleaner. Then pull that metal ring off, if it has one. Then have someone crank the motor over while you watch the injectors. Do they fire right away? Or do they not fire at all when hot. Then let it sit the 10-15 minutes to see of they fire right away or only after 10-15 seconds of cranking.

 

[Ricko1966]

Check the fuel pump relay jump it with a fused test lead. That truck has a redundant fuel pump circuit. Ecm is supposed to turn the fuel pump on for a couple of seconds to start then after that when the ecm senses a tach signal it keeps the pump running via the fuel pump relay. There is an oil pressure switch that is a redundant circuit to get you home if the fuel pump relay or its circuit fails. If the relay or its circuit is bad,the fuel pump will run,but only after you have enough oil pressure to close the oil pressure switch for the fuel pump. Oil pressure builds quicker colder.And a shot of either to start it would close the pressure switch immediately.

 

[Edelbrock]

Check the fuel pump relay jump it with a fused test lead. That truck has a redundant fuel pump circuit. Ecm is supposed to turn the fuel pump on for a couple of seconds to start then after that when the ecm senses a tach signal it keeps the pump running via the fuel pump relay. There is an oil pressure switch that is a redundant circuit to get you home if the fuel pump relay or its circuit fails. If the relay or its circuit is bad,the fuel pump will run,but only after you have enough oil pressure to close the oil pressure switch for the fuel pump. Oil pressure builds quicker colder.And a shot of either to start it would close the pressure switch immediately.

Could be BS, but it sure sounds reasonable to me. I would give that a try for sure. Could he test this by bypassing / overriding the oil pressure switch with a jumper?

 

[gmbellew]

There should already be a test lead off the relay to apply 12v that will turn on the fuel pump and bypass the relay. Red wire, if I remember right.

 

[Ricko1966]

Could be BS, but it sure sounds reasonable to me. I would give that a try for sure. Could he test this by bypassing / overriding the oil pressure switch with a jumper?

It's not B.S at all look at a wiring dighram for a TBI vehicle.

 

[Edelbrock]

There should already be a test lead off the relay to apply 12v that will turn on the fuel pump and bypass the relay. Red wire, if I remember right.

Nice. So its already designed to be easily tested and verified?

 

[gmbellew]

Nice. So its already designed to be easily tested and verified?

Yessir

 

[kychevy]

L

Also, have you checked the OBD1 codes? Is there a check engine light on?

Also, have you checked the OBD1 codes? Is there a check engine light on?

No codes or CEL

 

[kychevy]

So the problems started immediately after the impact? Like, you turned the engine off to exchange insurance, and then when you went to restart - the problem was there for the first time?

Correct