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insight on injectors

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leon

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this might seem a little stupid but I waould like to see what

you all think of this... 1999 f350 starts normally in warm shop

runs fairly good when warm, when cold....35f and lower will not

start, I have reploaced glow plug relay, it was smoked. verified

glow plug operation fuel supply to filter ok, (have not performed press test yet, when engine is cold (outside) and a

injector self test is performed you cannot hear any cycling of the injectors, when warm you can. this is a traded in truck with our used car dept. my initial thoughts are sticking injectors, cut my teeth on 6.0 and am not overly familiar with these older guys. what do you guys think?

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I'd be willing to bet that it is sticking injectors. We had a few really high mileage 7.3s with the same symptoms that were going to auction a few weeks ago. These trucks would not start at all if the temperature was near freezing. We ran a few litres of ATF in the oil for a few hours, then changed the oil... then they would start at well below freezing with no ether or block-heater... I don't know if the ATF would cause any damage, but like I said, they went to auction running fine...

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I'd agree, but make sure you check a few other things. First, glow plug amperage should be 190 initially on a cool/cold engine, and make sure cranking RPM is above 150.

 

I belong to the "replace the injector club", but I have a buddy who has fixed a lot of these by unbolting the magnets with the injector still in the head. Under the magnet collects a lot of steel-based sludge which makes the injector stick when cold. Clean this out, and voila! the injectors work correctly.

 

Good Luck!

 

/forums/images/%%GRAEMLIN_URL%%/grin.gif

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Also check the fuel heater, But I have found that the high mileage trucks should have the injectors replaced. The armatures(magnets) that Bruce is refering to might work but it's a crap shoot 50/50 chance that it will work. After that many miles and duty cycles the armatures wear out, I don't know exactly how many times a injector fires but like anything else is does wear out. Here at my shop we can rebuild these injectors, but have problems with the armatures. We have choosen to offer the new Alliant power injectors, Number 1 because of the warranty(2 years plus labor) and 2 because we don't have buy maybe 1 in a 100 that has a warranty issue. Versus about a 1 in about 25 with rebuilts.

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Also check the fuel heater, But I have found that the high mileage trucks should have the injectors replaced. The armatures(magnets) that Bruce is referring to might work but it's a crap shoot 50/50 chance that it will work. After that many miles and duty cycles the armatures wear out, I don't know exactly how many times a injector fires but like anything else is does wear out. Here at my shop we can rebuild these injectors, but have problems with the armatures. We have chosen to offer the new Alliant power injectors, Number 1 because of the warranty(2 years plus labor) and 2 because we don't have buy maybe 1 in a 100 that has a warranty issue. Versus about a 1 in about 25 with rebuilts.

I agree completely on all points. We switched to Alliant 5-7 years ago and have had 100% success with them since. I agree on the 50/50 but I was just pointing out another option.

 

Need any snow up there? Biggest storm in years, we have well over a foot since yesterday!

 

 

/forums/images/%%GRAEMLIN_URL%%/grin.gif

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Thanks for the input guys, I was leaning that direction and had

already told my ucd manager the probability of this being caused

by the injectors, I guess I needed some moral support, I doubt

that I will be repairing this unit but if I do I will let you all

know what happens, Thanks again!

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I agree with everyone else. If you can't hear the injector buzz, can you really expect it to work properly.

I also wanted to mention that we have seen a lot of 7.3's that either won't start, hard start or start and stall if parked overnight in the sub-zero and aren't plugged in. They are much harder to start if they have 15w40 in them. Also make sure this thing has 2 good batteries in the truck.

1 more thing, a long long time ago, I had a 7.3 that ran like total crap, barely idled, smoked, ect... The truck had 8 sticking injectors and here is how I found out. With the engine idling, I opened the drain valve on the water seperator and the truck smothed out and ran much better. With less fuel pressure, the internal parts in the injector can move easier.

Good luck!!!

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I see this on a regular basis in the international chassis. There is a link underneath the injector solenoid that wears. When the solenoid is engergized it is supposed to pull up on the link and allow injection to take place. When the link is worn the clearance is greater allowing more cold heavy oil to be between the link and the solenoid. The solenoid can not pull up the link to allow for injection. If there are no codes stored, and I can't hear the buzz during the buzz test, then I disconnect the glow plug system and get the engine to run on starting fluid. This will always trip the CEL with a 525 code, idm current high. International offers a tool kit that they will send to you that requires you to remove the solenoid and reshim the solenoid to the link. It can be done with the injector in the engine.

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a long long time ago, I had a 7.3 that ran like total crap, barely idled, smoked, ect... The truck had 8 sticking injectors and here is how I found out. With the engine idling, I opened the drain valve on the water seperator and the truck smothed out and ran much better. With less fuel pressure, the internal parts in the injector can move easier.

Good luck!!!

You know I forgot all about this, I had a wrecker that had the same issues you described and the hotline tipped me off about openning the drain trick.... Thanks for refreshing the memory /forums/images/%%GRAEMLIN_URL%%/cheers.gif

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  • 4 weeks later...

well, I got the job, replaced all 8, the truck was sold under the condition that it started cold, and it worked perfectly, thanks for all the input. on to the next one (so many trucks so

little time)

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