90 7.3 fuel injection problems

[robert bley]

My 91 F350 dies when I down shift.

I have been using vegetable oil as a fuel for a year or so. I have had some bad veggie in the tank and had problems with the engine starting. The last time this happened I replaced the fuel filter and had a heck of a time bleeding the air out of the lines. I have been reading the forums all day and finally found something that helped me get my truck running, Thank You.

I had to pull the cover off the IP and move the linkage inside back and forth for a while to get it moving freely. I checked both solenoids and they seem to be working even though the larger solenoid is cracked. After reinstalling the cover I bled the air on the filter housing (electric fuel pump replaced the original manual fuel pump) and then cranked the engine with the throttle wide open and several fuel lines cracked loose until I saw fuel around them. Within seconds of cranking it came to life after 3 days of trying.

Now I am back to my original problem which is engine stalling when I try to down shift. If I can keep the engine running when I take it out of gear it will stabilize and run.

I suspect problems inside the fuel distributor, but I have no idea how to troubleshoot it. Is there a deceleration circuit in the IP that could be clogged? Could the cracked solenoid be functioning poorly and causing this issue?

 

[icanfixall]

Welcome to the forum. Sounds like the metering circut in the injection pump is gummed up. Use a diesel fuel additive double dose to the fuel and it will clean up or.. Remove the fuel filter. Pour out the diesel in it or wmo your running and refill it with atf . Then run the engine for about 2 minutes and shut it down. The atf wil clean the internals of the pump. Let it sit for about 10 or 12 hours. Usually over nite works. Then the next day drive it hard. Rev it up and clean out the cob webs so to speak. If that does not fix it then its time for a pump....

 

['94IDITurbo7.3]

welcome to the forum!

 

[GOOSE]

Welcome to OB. I think Gary (icanfixall) is right on cue as usual. He won't steer ya wrong

 

[robert bley]

Thanks

I apreciate the quick response. I have been reading all day and learned a lot. I have had this truck for 12 years and had the engine rebuilt when I bought it. The IP was new and I never messed with it until recently.

I have had problems before with glow plugs going bad and had to replace them and the solenoid today to get it started after figuring out the bleed procedure.

I am running fuel cleaner now and this is the 2nd tank so I have already run about 10 gallons with cleaner. It got slightly better over time, but still stalls between shifts. Just so I am clear, should I fill the injection system then start the engine and drive it or crank enough into the engine to get to the injectors and let it sit overnight before driving the snails out of it?

I did not read anywhere in the forum about using atf until now so thanks for that, but what type is best?

Something else I have not read about is water fogging or hydrogen injection. I use hydrogen injection at about 1 lpm at the intake and it improves the mileage a little, but does not improve power noticeably. When I combined hydrogen and water fog I got seat of the pants improvement until my water setup froze and I had to disassemble it. I only did this for testing the effectiveness of fog versus water injection and fog won hands down. It also used very little water this way. I did not use any additives in the distilled water so there was no gain from alcohol, etc.

Not sure if this has been covered by any other members here in the past or what their results were.

 

[robert bley]

WMO vs WVO

I just wanted to clear something up. I am using waste Veggie oil. I have noticed some crud around the filler neck and I figure that is what is in the injector pump too.

I always use one tank for veggie and one for clean diesel. I start and stop the engine for a few miles on diesel then switch to veggie for the highway, etc.

My filtration is better now going to 1 micron, but I had a emergency and had to use an unfiltered jug which led to my running problems. It has gotten better but still stalls so it is probably orifice blockage or plunger problem in the IP.

 

[Shadetreemechanic]

As Icanfixall said it sounds like the metering valve in the pump. I would fill the fuel filter with diesel purge and run it long enough to get it circulating in the pump then shut it down overnight. You can do the same thing with ATF, but I have gotten better WVO cleaning with Diesel purge.

 

[robert bley]

I use regular diesel every night since I switch tanks before I shut down, usually a few miles from home. When I start up it is always on diesel. If I have problems with it running I always run diesel in both tanks until the problem clears or I fix it. I only supplement with wvo for the longer trips. I have noticed that some wvo is left in the filter after I switch tanks though because I can smell it in the exhaust even after I have run the tank empty and refilled with straight diesel.

Another note to consider is that as I switch tanks I am diluting the diesel in the rear tank by sending the fuel in the filter and lines back to the diesel tank. After a week or so I cant tell the difference. So I usually run the diesel in both tanks until I get rid of the french fry smell before I add veggie again. That has worked pretty well in the past unless I get some crappy veggie like I did this time. I was out of fuel and had to put in my emergency jug. Now all of my fuel is filtered down to 1 micron so this should not be an issue again, I hope.

NAPA has some stuff that I used before and it worked well. I will try that today and if it does not work I will soak it overnight with atf. I still have most of a tank with additive in it that I have to run out before I try something else.

 

[Shadetreemechanic]

You are running the exact same setup I do. How are your fuel guage sending units holding up? They were the first to go on my old truck and are now flaking out on my new one.
One of my vendors recently switch to "creamy blend" soy and its giving me fits at the moment. I put a blend of it in the rear tank two months ago and then it got cold so now I can only use that tank when it is warm out. Its got me thinking about a tank heater.

 

[basilbowman]

@ shadetree - Have I ever shown you my tank heater? It's pretty slick and not nearly as complicated as some of the other options out there.

 

[robert bley]

tank heater

I use a fuel line heater. I just ran copper pipe from the pump located just in front of the front fuel tank on the frame rail. The copper pipe wraps around the exhaust pipe all the way up to the manifold and is wrapped with exhaust tape. The output temp of the fuel gets around 110 deg F. On hot summer days it will get to 130 and in winter around freezing it stays around 100 F.

I replaced the crappy fittings with rubber seals that always leaked on the IP with copper compression fittings. So now I have copper pipe from the electric pump along the exhaust to the filter housing on the motor and then a short piece to the IP from the filter. I also have a filter before the pump on the frame rail that can be swapped out in seconds anywhere.

The added fuel temp with diesel helps my mileage too along with the hydrogen setup. If I could make my water fogger more dependable I could really increase the power and mileage.

I work with a hydrogen company that installs these systems on big rigs and normally get 30% better mileage. My system is a little more simple and less expensive, and still gets the job done. They inject it post turbo on the big rigs and get good results that way, but mine is IDI so it goes in just under the air filter.

Any fat left in the WVO will cause problems in the IP. The return temps are above 100 F so the tank eventually heats all the fuel to that temp and that lessens the solids, but I have already lost the tank sensor on my WVO tank. It reads over full all the time so I will have to replace the tank guts. the rear tank was screwing up too, but it is working now.

 

[basilbowman]

There it is - I've heard (and seen some small evidence) that using copper tubing will cause a reaction with SVO and you'll get gunk in your lines. My buddy used copper to run coolant bank into his tank, through a couple coils, and then back up as a sort of crappy in-tank-heater, and it was constantly covered with green gunk everytime he'd look in at his tank or snake it back out, and he was clogging fuel filters right and left. I used aluminum tubing on mine, a little bit more expensive, but much less reactive with SVO.

 

[robert bley]

I will keep that in mind and maybe switch to aluminum. I didn't think about the acids in the fat reacting with the copper. I need to pull the front tank and replace the guts so I will check the inside for crud and clean it before I replace the sensor and pickup.

What do you think about coating the parts in contact with the wvo? You think undercoating spray would hold up?

 

[basilbowman]

I don't know about coating it - you're supposed to use viton lined fuel line with WVO, I wonder if undercoat spray would hold up... I certainly would go and replumb it with Aluminum - but be warned, that ****'s expensive - a couple bucks a foot when you can find it. I ran mine HIH instead of wrapping it to minimize the amount I needed - 3/4" heater hose is a lot cheaper than more and more of that aluminum. But - I've had no problems with it, and it's pretty easy to work with.

 

[Shadetreemechanic]

@ shadetree - Have I ever shown you my tank heater? It's pretty slick and not nearly as complicated as some of the other options out there.

No, but I think I need to look. I towed this new F-350 back from Nashvegas on Sunday almost completely on diesel because of oil in my rear tank that was beautifully clear when I filtered it in September now won't pump. My filter light came on immediately when I switch to the rear tank until late in the afternoon when it warmed up and all problems disappeared.
I have never had this problem before on my winter 30-50% blends so I am also wondering if it is partially the electric lift pump not able to deal with viscosity.
It is a carrier pump bought on this site.