12v in 1990 f350 issue
 

ok ive had my truck done now for almost 2 years ever since i put the cummins in the ford iv had very low to no boost ive noticed my egts are higher than in the dodge and i dont have the low end spool up turbo makes at about 10-15 loades rely pushing it with the size turbo i have and fuel mods i was making 40psi+in the dodge since i started diagnosing i have done a 3piece ported manifold, ported turbo and custom high flow downpipe and no change could it be to small of fuel lines? thats the only thing else i can think of because you need fuel to make boost and boost to make more fuel?

I guess it could be possible. I would see where your fuel pressure is at and go from there.

well i do remember in the dodge with the pump turned all the way up i could flat black out a freeway in my older age im going for power not smoke. i turned the pump all the way up yesterday and still seems to be lacking the boost situation is still the same , i did an intake system check and no leaks

Do you have a draw straw or anything like that in the tank? Its possible the pickup in the tank could be too small causing a restriction.

fuel tank
 

I have heard that the screen in a gas truck will not let enough fuel through for a diesel might try a electric lift pump you have to move 90 gallon an hour the stock manual pump provides 90 gal hr at 7-12 psi depended on the rpm when my lift pump went out for the 3rd time I replaced it with one similar to this

ebay item # 390367125264

might be a good test or put a psi gauge on to test pressure

I posted a reply to this in the distress thread that i don't want to re-type

well the entire ford fuel system up to the lift pump is what im running and the truck was a 7.3 non turbo diesel im gnna check the lift pump screen and change the fuel filter and see what happens i dont have a draw straw but if its the fuel system thats next on my list i would like to find the cause before i get to redoing the entire fuel system especially with dual tanks

is it smoking worse?black?white?

well im leaning toward low fuel do to the fact the fuel components im running and the pump maxed out it doesnt smoke black like it should normally i have everyhting tuned so i dont get smoke but when i built this truck i havent had the boost to tune it yet anyway im almost debating on running a bypass line into a tank with actual 3/8 rubber fuel line and see what happens. i dont exactly know what size ports the fuel valve is being dual tanks but im sure it does restrict to a certain degree. with the mods im running i was pushing 45psi+ with it in the dodge

When I had my 1st Gen Cummins in my '93 F-250, I ran the stock Ford IDI diesel fuel system up to the lift pump on the Cummins and I never had a problem. However, when the sending units went out in the tanks, I dropped them and found out that the rubber funnel/baffel at the end of the pickup tubes were all "melted" and gummed up the end of the pickups. I did notice that when I put the 2nd Gen Cummins in and turned up the pump that it seemed like I could never get enough fuel to it with the stock 2nd Gen mechanical pump. I ended up getting an AirDog 150 and ran 1/2" line and a draw straw from the rear tank to the engine, and just use the front tank as a "transfer tank" with a small Carter fuel pump between it and the rear. I'm trying to come up with a way to make a 1/2" ID transfer valve assembly so I can straw the front tank and switch on the fly, but I've been pleased with the current system, especially since adding a 33 gallon rear poly Bronco tank.

hm thats interesting i didnt have any issues in the dodge i may end up doing that but other way use the front as the tank and the rear as storage for weight purposes. did you have all the mods when you had that issue with the secound gen motor? as far as low boost

When I swapped in the 2nd gen motor, I did the rack plug, 4k GSK, 16.5* timing, and 5x.012 injectors all at once. The motor would start and idle with the stock mechanical piston lift pump, but the minute you started giving it some throttle it would die...like it was starving for fuel. I spliced in a Carter electric fuel pump, still using the stock IDI fuel lines up to the pump, and that helped it a little, but it was still starving. I never did change the overflow valve, so that may also have had something to do with it. The AirDog 150 and 1/2" line solved everything though....and I still haven't changed the overflow valve.

Another thing to maybe check is the tank selector valve. I've heard of them wearing out the internals and cross contaminating fuel or pulling air in by trying to suck both tanks at once. I took my valve out when I did the 1/2" line to the rear tank, so I never considered it a factor afterwords... Just food for thought.

ok when i get back from my trip i will have to do some investigating im wondering if i could just stick a line into a fuel can to see if thats the issue im leaning away from the pump and more for the lines since guys run 600hp on stock pump

ok guys i just finished the fuel line i did a 1/2 in draw straw from the front tank and 1/2" fuel line to the lift pump and a 1/2 in vulcan big line kit wich is all the 1/2 in fittings and 1/2" line fo for between the lift pump to the fuel filter hauseing and from between the fuel filter housing to the p7100. i took it for a test drive and i seem to still have the same issue im gunna test drive it again today once i get the bed back on any thoughts as to my problem?

dumb question but did you re-clock the compressor housing on the turbo when you put it in, it could be binding the wheel?

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just some input on the fuel line size issue, im running the oem ford fuel system including the in tank sending unit, i just removed the pump, and replaces it with a section of pipe, still have the gas strainer, and factory size fuel lines all the way up to where the tank selector valve was, and i flow plenty of fuel.

its not turbo bind its spins freely if it bound it would hardly spin period i drove it yesterday and i max at 30lbs getting after it hard up a hll

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it seems it doesnt have the lower end boost it used to

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basically everythin i did between the ford and dodge its back to the way basically the dodge had. removed the industrial exhaust manifold went back to a polished stock manifold. 1/2 fuel lines all the way from the tank to the ppump, all the oil lines are basically back to stock like in the dodge it just doesnt seem to have the low end boost it did

bump any thoughts?

seemed to get her figured out injectors were shot so i threw in a set of SDX 5x.012, put a .010 head gasket on, new valve guides, seat sand seals and the boost gauge was shot. new 1/2" draw straw and full 1/2" fuel lines from tank to pump to fuel filter and to p7100

Do you have a guage telling you the fuel pressure at the injector pump inlet? If you can see it while driving & experiencing the problem, that should tell you if it's a fuel restriction. If you don't have a guage, try to get a filter restriction guage from a big rig shop such as Peterbilt or Freightliner.

The factory gas fuel strainer was a problem on mine, truck wouldnt even run when temp dropped below 35* or so, I think the fuel was too thick to flow through it. And even when warm, after I pulled the plate, if i went WOT, I would cloud out the highway behind me white smoke because of lack of fuel. Yours may not be a problem, I would just keep an eye on it.

94cummins12v, doing better now?

oh ya runns like a dream now this sdx injectors have more pull to them than the ddp 90s did. one of the injectors wasnt even sprying just dribbling and 2 of them had a clogged nozzel

So the DDP's went bad on you?

And yeah that might cause some performance issues :D

Glad you got it figured out, Badass truck :c:

ya they were about 3 years old i herd from the local performance diesel shop the ddp arent as good as they used to be he switched from ddp to SDX becasue of there poor customer service and he has had a few sets go bad after a few thousand miles and they wont exchange them so he switch everything to SDX i honestly like these SDX 5X.012 better than the ddp 90's they seem to smoke less and have lower egts towing

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yep she runns like a dreem now hits 40-50 lbs of boost like it should had the throttle response again little smoky till the turbo hits but im happy with it now welded my new mirror brackets for the flip out dodge tow mirrors and replaced the driver fender now shes off to body and paint shop to get a complete body and paint job

i hate to bring up but did you check fuel cylinoid for opeaning all the way. i had same problem and spent 2 weeks looking for problem after fixing fuel cylinoid my truck was like totaly difrent truck.

yep fuel silinoid wasnt the culprit check it along time ago :tttt: thats why i posted this morning that shes up and running great again:c: