Hi guys, I'm confused - after spending $900 for a local truck shop to diagnose my '97 F450, they said that the air in the fuel is coming from an injector(s). The truck has no power. It starts OK, makes no smoke, stalls repeatedly. After all the usual stuff, from new filters to a new MAP sensor and fuel pump, there has been no change. When the fuel fed from a separate source directly into the pump, and returned into a coffee can, it has A LOT of air coming out. The shop said that a bad injector could do this. I know that an injector that fails in a normal manner won't make the truck quit, but could a bad o-ring or stuck injector allow pressurized air to back-feed into the fuel system? The truck only has 120k, it did have bad fuel a month ago, I think the problems are related. Any help or suggestions would be appreciated. Thanks.

 

Only time I have seen this, happend several times too, is when a DIY customer messed something up and broke a dowel pin or 2 puting the injector back together. The pin and/or parts of the pin get caught in the fuel components and will indeed allow cylinder pressure to enter the fuel system.

I have never heard of it happening out of the blue on a stock truck, though I suppose it could happen. Air in the fuel would just about have to come from the cylinder, diagnosing which injector would be tricky at best...

 

Thanks for the reply, the folks I've talked to agree that this is indeed rare, which is why I'm not sure if it's an injector issue. The injectors are stock, but the truck did have some bad fuel in it when I bought it, looked like fuel oil, not off-road, clogged the filter every 3k miles. I could isolate the bank, and maybe find the culpit injector, but while I've got it apart and taking the chance of other questionable injectors in the near future, I was leaning toward sending them all to Bean's, if nothing else than for new o-rings. It's funny that the brand new fuel pump is not holding fuel in the filter housing, we thought the check valve might be stuck. The fuel level drops faster than a flushing toilet, which is about how fast my wallet is being emptied. There is no fuel leaking anywhere externally. The oil level is a bit high (1/2qt, but I could have overfilled it slightly when I changed oil), but 3 or 4 fuel housing dumps should have made more of a difference. I can't imagine that fuel is leaking past a bad o-ring that fast.

Anyway, any additional thoughts would be appreciated, I'm in over my head!! The dealer won't look at the truck because it's been modded to run on veg oil, and the fuel lines are re-routed. With the fuel system isolated and running from a 5-gal bucket of fresh fuel, air is still coming out the return side - a lot of it. It starts returning with a steady stream of fuel, but within a minute it's blowing mostly air.

Just what I wanted for Christmas - new injectors...but not on my work truck, I wanted them on my '95 F350!! Arghh..

Thanks for your help!!

 

I would check with DZL JIM on the injector work, he answered your question and does jam up injector work, plus he sponsors our section.

 

Oops, I didn't read who you were!!! I LIVE in C******!! Man, if you could give he a call or email me I'd really appreciate it. I know I've seen your truck around, awesome!! You'd probably recognize my '95 F350 crew, Reef Green, with Ranch Hand bumpers, slightly modded (brand new base/clearcoat, a whole 'nother project where I was in way over my head...). Or the white O.J. Bronco, '96, almost new condition.

PS, beers and dinner are on me at Hambden Inn, anytime you want!! Plus all of my truck business. Kronk's diagnosed the truck, along with my amateur input.

Thanks, Dan
whitetailwoodsfarm@yahoo.com
635-0230

 

Thanks, Plowhand, I was in the middle of replying to DZLJIM, missed your message, I will indeed get with him on this, do you have a email address for him, it's not in the links or his profile?

A second recommendation was very helpful in deciding a course of action (going with DZLJIM), thanks for the input, the guys on this site are great!

 

Oops, double post.

 

Are you still using the stock pump and filter canister with your WVO conversion?

I was reading an article the other day at this site ...

Mighty Auto Parts --> Tech Tips Archive

Scroll down to TT112 (TT= tech tips). It is in PDF format and page 2.5 - 3 deals with our diesels. Bottom line they are pointing out the importance of the regulator screen filter being kept clean. You can see this screen by removing the filter and there will be a round hole in the canister (drivers side) towards the top of the canister. Get a flashlight and q-tip without the cotton and gently scrape any crud that is built up on the screen. Worth a shot.

 

Thanks for the advice, I took the FPR apart, the screen was perfectly clean, I cleaned it then the WVO kit was installed, and the check ball seems to be working freely. No difference, unfortunately, that would have been too easy!! The truck has 20k on WVO, with no problems until now. I change diesel filters every 5k, the WVO filter needs changing about every 700 mi. It actually runs slightly better on WVO (viscosity??). Whatever happened did so suddenly, it wasn't a gradual loss of power, although it is definitely getting worse. The only code it threw was for the BPV, which has been gutted. Injector removal isn't as bad as I thought, with a lot of help from the guys on this site, but it IS getting hard on the wallet.

Thanks again, DS

 

Dan,
Pretty sue I've been by your place a million times (Claridon-Troy Rd.?)
I'll try to give you a ring in the next day or 2.
I'm not really trying to sell you on anything, but going through the injectors might be a good place to start since they do need overhaul every now and again anyway. Just something to think about.
Kronk's is (was?) a great place to go to, but not sure how PSD specific their knowledge is.
In 2001, my Black truck died on me and I had it towed to them. they diagnosed the problem as a 'bad injector', the truck only had 60k miles on it and was 1 month out of warranty. Cost me $550 for a 'new' injector (which was a Ford reman = JUNK) and $800 in labor.
The day after I picked my truck up from them I found a bunch of forums online, and none of my trucks have ever been to a shop since.

 

A quick update from my end.
I rebuilt Dan's injectors a week or 2 ago. Those Plunger & Barrels were the worst I have ever seen. The fit was so loose they basically flopped around, and oem spec is around .00002" ( 4 microns or so?).
When I soaked them in diesel fuel and tried to push the plungers into the barrels they would spit up bubbles, so I imagine that's where the air was coming from.
Hopefully Dan will be along when he gets them put in and give us his update.

 

Rosewood diesel rebuilt the injectors and the problem is fixed. Ends up the plungers and barrels were worn, enough to let a small amount of compression air back-feed into the fuel system. My very amateur guess is that the truck would run, although with some loss of power, on one or two bad injectors, but if another starts to leak too much air gets into the fuel system. Thanks for all the input, guys!!