TBI I need help

[GR Jonesy]

I am new to this forum I’m 72 years young and had chevys my whole life. Have had this truck for about 12 years. TBI 350 auto four wheel drive 1987. My problem is I cannot get it to start. Started out it would not idle. After replacing several parts now it will not start. This is what I’ve done so far. Replaced TPS IAC plugs MAP sensor injectors and connectors ;checked fuel pressure 16 lbs before the filter new filter; I have spark I have 12 volts at the injectors noid light flashes while cranking so sometimes it sprays sometimes not. I also tried to set the base idle think that may be where I messed up. Any help would be appreciated and thanks for reading this

 

[geocrasher]

Make sure the reluctor ring and pickup in the distritubor is good, and also make sure timing is correct.

 

[Mr Clean]

 

[squaredeal91]

Welcome from Oregon!
And please humor me. IF you haven't messed with or replaced coolant sensor.
Unplug your coolant temperature sensor on intake manifold, and try to start it.

 

[GR Jonesy]

I replaced the coolant sensor and cleaned the two grounds there. The distributor is only about 2 years old I replaced the ICM cleaned the cap and rotor. I also put dielectric grease in the connections ????? How would I check the pickup coil without pulling distributor can I do it with a multimeter

 

[squaredeal91]

Did you grease the icm? I like the pickup coil as suspect

 

[GR Jonesy]

Yes I did with dielectric I have good spark

 

[fast 99]

check injector pulse if no fuel spray. Can be done with a test light. With key on should have power standing on 1 side. When cranking across both terminals should flash. Or get a noid light, they are inexpensive.

 

[GR Jonesy]

I have pulse with a noid light. But I don’t know how bright the light should be if that makes since. Also if I put 12 volts to the injectors and touch to ground they will spray when the key is on

 

[vr1967]

See if these help, from the 88 service manual

I had an issue recently, that we thought was a fuel issue when it ended up being the MAP sensor.
Can post a quick to check it with just a multimeter

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[GR Jonesy]

I replaced the map sensor but knowing how to check it would be helpful. Also I will go through these check list

 

[fast 99]

In the future it would be advantageous to do a search before attempting a repair. This problem has been discussed several times here. When you start shot gunning parts at an issue you may inadvertently create a new problem making diagnosis harder. Many new parts are total junk. In most cases a used GM part will be more likely to function than a new offshore piece.

Follow the diagnostic tree in the previous post to the letter.

 

[KnuckleBuster]

I replaced the coolant sensor and cleaned the two grounds there. The distributor is only about 2 years old I replaced the ICM cleaned the cap and rotor. I also put dielectric grease in the connections ????? How would I check the pickup coil without pulling distributor can I do it with a multimeter

--Two grounds at the coolant sensor? It doesn't have 2 grounds. Are you sure it was the coolant sensor? Should be one yellow wire and one black.
--The dielectric grease that comes with the ignition module is NOT for the terminals/connector. It should be applied to the underside of the module to help dissipate heat.
--The pickup coil is easily checked with an ohmmeter without removing the distributor. Disconnect it to measure resistance, which should be 500-1500 ohms, with no continuity to ground. I don't think you'll find a problem there since you said you have spark.

Just an observation...a mechanic could have diagnosed this for less than the money spent throwing parts at it. Might have even fixed it. Your choice, of course. Good luck!

 

[Maknwine]

@GR Jonesy
This may seem silly, but any chance you could go back and replace the old parts back excepting the injectors("Replaced TPS IAC plugs MAP sensor"). Just in case you can get it back to a rough idle at least.
But first, go thru the checklist procedures probably smartest thing you can do.
I'm wondering if the rough idle could have been caused by a loose distributor hold down bolt, might be worth a wiggle test on that.

 

[GR Jonesy]

Knuckle buster there are two grounds for the ECM that grounds on a bolt next to the coolant sensor. I did put the enclosed grease under the module. I also put some I had on the connections because a post I read said it cured his issue but I’m not sure it was a good idea lol. I kinda agree with you on the pickup coil because I have spark thank you sir. Maknwine it was more than a rough idle it would not idle at all but I am wondering if it could be a timeing chain issue. Thank you also for your response