7.3 idi crank but no start

[grahamal092]

I have a 1991 F350 7.3 idi. About a month ago I drove the truck to a gas station and left it idling for about 5 minutes and it just shut off like someone reached in and cut the key off and I could not get it to fire back up what so ever. I ended up having to get it towed back home and I am now trying to diagnose/fix the problem. The engine turns over fine but I noticed that the wait to start light no longer works and I no longer hear the glow plug relay/controller click like I use to so I replaced it with a new one and still nothing. I cracked open all of the metal lines going into the injectors and I have no fuel coming out of them while turning the engine over so I salvaged a fuel shut off solenoid that I know works from a different truck that I have and still no fuel from the metal injector lines. I also noticed that I do not hear the audible click from the shut off solenoid when the key is on. I do however, have fuel flowing from the return lines and the schrader valve at the filter while the engine turns over. The truck also has a small aftermarket electric fuel pump on the passenger fender that I also no longer hear come on when the key is on. Also, im not sure if it is related but the last time i drove the truck i noticed the tachometer was not longer working. I am fairly new to these trucks so I apologize for any ignorance and any information or advice will be very much appreciated.

 

[Nero]

Welcome to the forums.

You'll have fuel flow at the returns because the filter head in its stock form has a bleed port which flows to the return.

You'll need to check why you have no power at your fuel shutoff solenoid. If I had to bet, you either have a burned fusible link near your start relay on the fender, or the main engine harness connector melted.

 

[IDIBOBS]

Electrical problem. I’d start with The main feed from the battery to the body harness. I’d bet you have no power to the ignition box. If you have power into the ignition switch box then I’d bet you have no power out of the box. Gonna have to get a test light or better yet a power probe and see what’s what with the wiring.

 

[Jesus Freak]

Welcome to the forum! And you gotta bad wire somewhere. These old trucks have a way of building up corrosion inside the battery cables right next to the battery terminal connector...... it's weird. Jiggle the cable a bunch, check for continuity with a electrical meter. You got this!!!

Edit: don't worry about being "ignorant"....we can fix "ignorant"...... it's "stupid" and Dodge that there's no hope for...

 

[Nero]

Electrical problem. I’d start with The main feed from the battery to the body harness. I’d bet you have no power to the ignition box. If you have power into the ignition switch box then I’d bet you have no power out of the box. Gonna have to get a test light or better yet a power probe and see what’s what with the wiring.

Mind showing us where the ignition box is?

 

[grahamal092]

Welcome to the forum! And you gotta bad wire somewhere. These old trucks have a way of building up corrosion inside the battery cables right next to the battery terminal connector...... it's weird. Jiggle the cable a bunch, check for continuity with a electrical meter. You got this!!!

Edit: don't worry about being "ignorant"....we can fix "ignorant"...... it's "stupid" and Dodge that there's no hope for...

Thank you for the reply. I replaced the positive battery cable that goes down to the starter and across to both batteries about a year ago because the ends were brittle and falling apart. I haven't touched the negative cables though. The engine turns over strong it doesn't seem like it has any electrical resistance caused by a corroded battery cable.

 

[grahamal092]

Welcome to the forums.

You'll have fuel flow at the returns because the filter head in its stock form has a bleed port which flows to the return.

You'll need to check why you have no power at your fuel shutoff solenoid. If I had to bet, you either have a burned fusible link near your start relay on the fender, or the main engine harness connector melted.

Where is the main engine harness connector located?

 

[IDIBRONCO]

Where is the main engine harness connector located?

It's on the passenger's side inner fender. There's several wires on both sides of it. You can see the engine side where it runs over the top of the passenger's side valve cover.

 

[DougBoy66]

I had an experience somewhat like @grahamal092. During this build engine starting and running great. Then one day I go to start. No wait to start light so I try to start without it. Only cranks for as long as I dared. Even bought a new glow plug controller. Then I saw that the engine wire harness had came where it plugs in by the engine bay fuse box. Plugged it back in and everything was back to normal but, before that discovery I was checking fuses wires on the opposite side of the motor. Kind of embarrassing for me but what a relief when I found the actual issue. It really wasn't very obvious to see

 

[DougBoy66]

Wow I guess I should have read this earlier another embarrassing moment

 

[IDIBRONCO]

Wow I guess I should have read this earlier another embarrassing moment

It happens!

 

[KansasIDI]

it's "stupid" and Dodge that there's no hope for...

No hope? Perhaps you don’t remember my vehicular background…

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Sorry about the derailment, I just couldn’t help myself… part of being ‘stupid’ from Dodge

All in good fun, just playing on your words to make fun of me

 

[franklin2]

I have a 1991 F350 7.3 idi. About a month ago I drove the truck to a gas station and left it idling for about 5 minutes and it just shut off like someone reached in and cut the key off and I could not get it to fire back up what so ever. I ended up having to get it towed back home and I am now trying to diagnose/fix the problem. The engine turns over fine but I noticed that the wait to start light no longer works and I no longer hear the glow plug relay/controller click like I use to so I replaced it with a new one and still nothing. I cracked open all of the metal lines going into the injectors and I have no fuel coming out of them while turning the engine over so I salvaged a fuel shut off solenoid that I know works from a different truck that I have and still no fuel from the metal injector lines. I also noticed that I do not hear the audible click from the shut off solenoid when the key is on. I do however, have fuel flowing from the return lines and the schrader valve at the filter while the engine turns over. The truck also has a small aftermarket electric fuel pump on the passenger fender that I also no longer hear come on when the key is on. Also, im not sure if it is related but the last time i drove the truck i noticed the tachometer was not longer working. I am fairly new to these trucks so I apologize for any ignorance and any information or advice will be very much appreciated.

I would get a meter or testlight and verify you do not have power at the fuel shut off on the injection pump. From your description it sounds like you don't.

That is powered from a red/lightgreen wire. You can see the fuel shut off solenoid in the upper right corner of the diagram.

You will also see this same red/lightgreen runs all over the top of the engine powering all kinds of stuff. But my main suspect would be additions by previous owners. Most people, including me, add a small electric pump and tie it to this red/green wire. Look at their wiring first, make sure it's good. I have also had these little pumps have catastrophic failures and start blowing fuses. So you might want to disconnect it.

This leads us to the next thing, the fuse. I will have to look again, but I know the early trucks did not fuse this wire, they used a fusible link. I am not sure where it's located, may someone else knows.

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[franklin2]

P.S. You can see the fusible link in the diagram above, to the left of the "engine connector". It's a 20 gauge fusible link.

 

[franklin2]

Ok, I found out this is fuse link "X". Shown in the diagram below.

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