Truck won't start?

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mybluetoy

mybluetoy

10 Year 15 Year
Joined
Dec 9, 2007
Threads
59
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346
Location
Grand Rapids, MI
Website
www.unemployedfilms.com
I recently switch engines. I have a 1986 efi. I know the motor is good. It will fire and then quit. There is no oil pressure reading, could the computer be telling it to quit for safety reasons? I will try and switch out the oil sending unit. Any other suggestions please post. This is my daily driver and I need it on the road. Thank you John.
 
There is no input to the EFI ECU for oil pressure, it will keep running till it siezes if you really have no pressure.

Starting then dying is usually something with the MAF on top of the air box. Either you forgot to plug it in (BTDT) or there's something wrong with it. Jumper the Fp and +B pins in the diagnostic connector with a paper clip, then see if it stays running, this will force the fuel pump to stay running.

Report back.
 
Won't stay running

Im helping out with this truck, we tried a comlpetly different Mass air flow sensor, no luck, the fuel pump is hot wired to ignition...so works fine when cranking and key on, tried a differnet igniter with no luck, double checked igniter wire to distributer cap, looked for vaccum leaks...none, cracked open the door on the mass air flow sensor, nothing, ...it has fuel in tank..:)

I believe the cold start injector is what is causing to run and the main injectors are not working???

Any thoughts anyone?
 
Have you checked for any codes stored in the ECU?

Have you checked for spark?

I'll go ahead and state Wristy's standard suggestion: check the ground to the engine, under the intake.
 
I've been out there all day, the truck starts idles and then quits. If you give it gas it quits right then otherwise it runs for about three seconds then it quits. Need some help. Like red toy said he is helping me out. We are about to go and disconnect the cold start injector to see if that is the only one to make it run. Will let you know the progress.
 
You have yet to test for the basics like spark/fuel. Pull the plug wires and test for spark. Then pull the injectors and test for fuel.

Was the truck running before?

You have not stated the year of your truck and/or the condition of your old motor.

Details please.
 
make sure the plug off the distributor is tight. the coil wires are tight, firing order is right. 1342.

make sure you have clean good gas and a clean good filter. make sure you didnt dent the last filter bt over tightening it, as that can cause a restriction and it to bypass the filter all together.


the cold start injector only fires off once. eliminate this in your trouble shooting by disconnecting it. and follow KLF's advice where he quoted me :)
 
Jukelemon said:
You have yet to test for the basics like spark/fuel. Pull the plug wires and test for spark. Then pull the injectors and test for fuel.

Was the truck running before?

You have not stated the year of your truck and/or the condition of your old motor.

Details please.
Click to expand...

Has spark, wires are new, the motor ran before, gas is new and clean, it is a 1986, has 222K miles. We pulled the the cold start injector and it would not start, this leaves us to believe that the other four are not working. We put a test light to it and we're told it should pulse, it did not. It was a constant light. Tired and will try again in the morning. What do you mean by pull the injectors?
 
WristPin said:
make sure the plug off the distributor is tight. the coil wires are tight, firing order is right. 1342.

make sure you have clean good gas and a clean good filter. make sure you didnt dent the last filter bt over tightening it, as that can cause a restriction and it to bypass the filter all together.


the cold start injector only fires off once. eliminate this in your trouble shooting by disconnecting it. and follow KLF's advice where he quoted me :)
Click to expand...

I will check the bolt to make sure it wasn't over tighten in the morning. Everything else has been checked twice?
 
mybluetoy said:
Has spark, wires are new, the motor ran before, gas is new and clean, it is a 1986, has 222K miles. We pulled the the cold start injector and it would not start, this leaves us to believe that the other four are not working. We put a test light to it and we're told it should pulse, it did not. It was a constant light. Tired and will try again in the morning. What do you mean by pull the injectors?
Click to expand...

the cold start injector only has a single shot of voltage to fire the injector. other than that, it remains off, till the key is cycled again.

its hard to test the injectors with a test light, but will tell you if they work. what i mean is, you should see a pulse, pulse.. when using the right tool, a noid light, but with a regular test light, it will stay lit up.

the temperature sensors are bastards, and it may be the problem too. check the ohms on it.

you pull codes?

check for vacuum leaks again.

pull a plug. is it wet? could be leakin cold start injector, injectors could be shorted.

tell me what the ambient temperture is out there, and i will tell you the ohm spec to test your water temp sensor
 
We know its getting spark because it runs for 3-5 seconds on the cold start injector

We added another ground to engiento be sure its well grounded besided the original

Hot wired fuel pump to 12v on ignition (energizes when key on)

cannot pull codes because this harness does not have the diagnostic box

Engine will run on starting fluid as long as you spray it

Double checked for vacuum leaks

Cracked open door on mass air flow sensor when starting ....no difffernece

Will use a noid light to propperly test injectors

Engine ran days before the transplant

Working on inside 50 degrees F

switched ECM, Mass Air Flow Sensor, ignitor with know good ones

Basically we believe the signal is lost somewhere in between the distributor to the the computer and the computer is not sending the pulse signal to the injectors

Thanks again for any help
 
Last edited:
Yeah, sounds like a mass failure in the injectors i.e. all of them not working would point to a general issue like an ignition circuit issue.

What I meant by pull (test) the injectors is to see if they work i.e. spray fuel.
 
The injectors are run in pairs, IE: 2 wires from the computer... So if none of them are working... My guess is a bad common ground, or a bad power feed (depending on which way they are wired...)... or a lack of signal to the computer to tell it to fire the injectors.
 
runs

Thanks everyone for ther comments, a friend helped to power the ECU, which is the problem, that is... by passing a relay. The 12v jumper to the ECU now has power to send the pulse signal to the injectors....making it run like it should :D
 
red_toy said:
Thanks everyone for ther comments, a friend helped to power the ECU, which is the problem, that is... by passing a relay. The 12v jumper to the ECU now has power to send the pulse signal to the injectors....making it run like it should :D
Click to expand...

Not to beat a live horse, but how did it run at all IF the ECU was not powered i.e. no B+. I don't understand that piece.
 
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