fuel problems

9cummins4

9cummins4

average joe
Joined
Oct 23, 2009
Messages
48
I'm new to the site so I would like to say Hi and see how this works. I have a 94 dodge cummins 2500 4x4 5 sp with 130,000 miles on it. I have dumped some $$ into it and it seems that there is no light at the end of the tunnel.
Here's a list of parts, ATS aurora 3,000, #5 tst plate, Afc mods, 4"exh., s&b cold air, 75 hp ddp inj., 181 dv's, 4k gov spr, 60lb v-spr., BD exh. brake, 16.5* timing, kdp fixed, solid steel adj. trac bar, and a leveling kit with 285/75/16's bfg's a/t.
I know the first thing you will say is you need a clutch and i have one on it's way. I have a problem with my truck on the top end of the RPM range. When I'm in the pedal deep at 3000rpm the motor starts surging like it's not getting enough fuel. My factory lift pump was bad and i installed a new one and it helped out a lot. Before I replaced the lift pump it would surge around 2,400 or so. With 4k gov spr. I should have more top end so what do you guy's think? I was thinking that my fuel plate was to little and maybe I should go with a #4 plate. I was also wondering if the factory lift pump would support the 4k spr. ???
 
it could be a couple of things, i dont think it is your fuel plate, if you are have a surging issue, that would be more like a governor issue with the pump, i see you have 4k springs, do you have a problem with the truck idling? it may be possible that the gov. springs are not adjusted right. if they are, it could acutally be something wrong with the govenor in the pump. even though you just put a new lift pump on the truck, it wouldn't hurt to check the fuel pressure at wot, should be no less than 20psi. if it is dropping off, you have a fuel supply issue. hope this helps!

Wes
 
I would check the fuel overflow valve on the back of the injection pump. The internal spring is known to cause problems holding proper fuel pressure when it gets a little worn. Either disassemble the overflow valve and stretch the spring or add another spring from a bic pen or just buy a new overflow valve.

An inexpensive test to diagnose the problem would be to hook up a fuel pressure gauge at the injection pump. I would run off to Autozone a buy a cheap sunpro oil pressure gauge kit for 22 bucks. Use the fittings and nylon tubing and mount the gauge right under your driver side windshield wiper blade. Go take your truck for a test drive and see what the fuel pressure is doing when you truck is surging and having problems. If you have good pressure, your problem is most likely governor related and not fuel related.
 
my truck also does this. was doing it badly after i took out the stock injectors and put in my 5x.018s. my lift pump was ticking so i figured it was going bad. i just finished installing my new airdog 150 today and the problem got a lot better but it will still surge (acts like a rev limmiter cutting out) up top. i think it may be my turbo because it only does it when it get up to 60lbs. and its only an hx35 so i think it could be related. but i see you have an aurora 3000 so now im wondering about my theory.

Big Blue24 said:
I would check the fuel overflow valve on the back of the injection pump. The internal spring is known to cause problems holding proper fuel pressure when it gets a little worn. Either disassemble the overflow valve and stretch the spring or add another spring from a bic pen or just buy a new overflow valve.

An inexpensive test to diagnose the problem would be to hook up a fuel pressure gauge at the injection pump. I would run off to Autozone a buy a cheap sunpro oil pressure gauge kit for 22 bucks. Use the fittings and nylon tubing and mount the gauge right under your driver side windshield wiper blade. Go take your truck for a test drive and see what the fuel pressure is doing when you truck is surging and having problems. If you have good pressure, your problem is most likely governor related and not fuel related.
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how would the overflow valve cause surging. i have stretched the spring in mine before but who knows if something is wrong with it now. does that valve just control the ammount of fuel being returned to the tank? so if its a weak spring it would be dropping fuel pressure too early and not allowing the motor to get an addequate ammount of fuel?
 
stubz616 said:
my truck also does this. was doing it badly after i took out the stock injectors and put in my 5x.018s. my lift pump was ticking so i figured it was going bad. i just finished installing my new airdog 150 today and the problem got a lot better but it will still surge (acts like a rev limmiter cutting out) up top. i think it may be my turbo because it only does it when it get up to 60lbs. and its only an hx35 so i think it could be related. but i see you have an aurora 3000 so now im wondering about my theory.



how would the overflow valve cause surging. i have stretched the spring in mine before but who knows if something is wrong with it now. does that valve just control the ammount of fuel being returned to the tank? so if its a weak spring it would be dropping fuel pressure too early and not allowing the motor to get an addequate ammount of fuel?
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Yes sir, The Over flow valve does return to the tank. When it opens it kills your fuel pressure. The only way to really tell if you have a problem is to monitor it with a fuel Pressure Gauge. $.02

Lynn
 
stubz616 said:
i think it may be my turbo because it only does it when it get up to 60lbs. and its only an hx35 so i think it could be related
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really?? why would you run a hx35 so far out of it's efficency range?? im baffled that it hasn't blown apart yet. would you like to take a guess at how hot the air is coming out of that turbo at 60 psi? probably hot enough to melt something! not trying to be a dick here, but i think it is time for a different turbo, you are going to make alot mroe power with a turbo that can make that kind of boost, without superheating the air, all that hot air is just killing your power man. ontop of that you are running a super fine line with that turbo surviving any longer. Beers!

Wes
 
I was talking to a local kid this week and he was asking me why he has went through 3 turbos in a matter of a month....he is running HX-35's and he is pushing them to 55-60psi...he has blown 3 compressors and can't figure out what is wrong....
 
Dusterb318 said:
I was talking to a local kid this week and he was asking me why he has went through 3 turbos in a matter of a month....he is running HX-35's and he is pushing them to 55-60psi...he has blown 3 compressors and can't figure out what is wrong....
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Tell him he's a dumbass.
 
I don't know a lot but I know 38psi is the max range for the 35.....I just shook my head and said dunno know man. Got in my truck and left
 
i know 60 psi is pushin it. i can't afford a new one yet. im gunna buy a silver 64 or a silver bullet after im out of school. i just keep it under 40lbs so it will last. i know that 9712valve shot his wheel right out of his and broke the compressor housing at 60lbs. i know the dangers of the stocker and i know i can make more power with a bigger charger but my wallet doesn't agree with my needs.
 
ok that's cool man, just be smart, id hate to see something happen to your engine because your turbo blew up. i wonder how hot the compressor outlet is at 60psi??? 450-500deg.F. me thinks.
 
Thanks a lot for the feed back. I talked to a Dan at DDP today and he thinks it is more than likely the over flow valve and I looked up online how to check the valve so I will try it tomorrow. When I took the truck to get it tuned we did a fuel pressure test and it only had 3.5-7 psi at idle. If I used a oil pressure gauge could i hook it up on the opening on the fuel filter housing? thanks again for the feed back
 
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