7.3 IDI

[Northman]

I have one here that has me stumped mainly doe to a complete lack of experience with these.

Customer says it runs very rough when first started (cold) and gets better after it warms up. I have checked the glow plug operation and they seem to be working fine. (circuits will light up a headlight and all ohm out.) I did a compression test due to the amount of "dirt" I could see in the intake manifold with the air cleaner off.

bank 1 has a high of 410 psi and a low of 300 this is outside Ford's guideline. but I don't wanna rip this thing open without being more sure end result is gonna fix the customers concern. It is a farm truck the owner wants to sell but he doesn't want to sell a turd.

 

Customer has had some things done by others trying to fix this like; injector pump off and sent in for repairs, injectors replaced, all new glow plugs, replaced glow plug harness, glow plug relay. injector cleaner. from what he says this all began one day when he ran it out of fuel (a few years ago)

 

I don't want to be just another guy who has thrown parts at this thing.

[Bruce Amacker]

I have one here that has me stumped mainly doe to a complete lack of experience with these.

Customer says it runs very rough when first started (cold) and gets better after it warms up.

 

This is perfectly indicative of low compression but could also be an injector or glow plug problem. (but it seems like this should be ruled out)

 

I have checked the glow plug operation and they seem to be working fine. (circuits will light up a headlight and all ohm out.)

 

Test amperage on each GP and compare them. An amperage check is the only true dynamic test for an electrical heater system of any type. I used to know how many amps an IDI GP pulled, but I CRS. I will agree that if they have continuity they are usually good.

 

 

I did a compression test due to the amount of "dirt" I could see in the intake manifold with the air cleaner off.

 

This is not good, it's dusted.

 

bank 1 has a high of 410 psi and a low of 300 this is outside Ford's guideline.

 

Yes, this is a huge problem. Anything under 350 is not allowed and 300 won't run when it's cold.

 

but I don't wanna rip this thing open without being more sure end result is gonna fix the customers concern. It is a farm truck the owner wants to sell but he doesn't want to sell a turd.

 

OK, Mr. Farmer, you own a turd. What do you want to do with it?

 

 

Customer has had some things done by others trying to fix this like; injector pump off and sent in for repairs, injectors replaced, all new glow plugs, replaced glow plug harness, glow plug relay. injector cleaner. from what he says this all began one day when he ran it out of fuel (a few years ago).

 

Yea, yea yea, blah, blah, blah. Like I never heard a customer lie to me before. He just doesn't want to believe the truth.

 

I don't want to be just another guy who has thrown parts at this thing.

Throw a long block at it. If you want to do some diag, loosen injector lines when it's cold to identify what's not running and see if that agrees with your compression test. You could also loosen or remove the exhaust manifolds and start it cold to identify dead holes by what's smoking. Swap injectors and see if the misfire moves. On IDIs it's almost impossible for a pump to cause a dead hole. I'd bet money he picks this thing up and doesn't do anything to it, I doubt it's cost effective to go inside this engine.

 

Good Luck!

 

[Aaron]

+1 on the long block, or telling him to sell it as-is.

[Mekanik]

Aaron, I had an IDI a long time ago that was doing the same thing. I had air in the fuel lines due to a rusted fuel pick up that was leaking a little bit of fuel too. What I did to diagnoss it was put a piece of clear tubing on the injector pump return fitting in line with the return hose.