fuel and throttle power loss


Asked by Feb 26, 2016 at 07:01 PM about the 1994 Dodge Ram 2500 Laramie SLT Standard Cab LB

Question type: Maintenance & Repair

Loss of power after warm up. Sounds
like engine gasping for air...definitely
stops combustion at twenty percent
throttle. No clogged Cat. New plugs.
New air filter. Injectors clean. New
TPS...MAP...IAC. Before I changed
plugs and removed cat no codes. Cat
is replaced...10000 miles.on
pump.filter in tank with pump. I am
now getting codes for MAP, TPS, and
o2 sensor. What is the problem? Has
standard 5 speed tranny. Idles nice.
Starts without problem. Doesn't die.
But starts puking under driving load.
Won't go up hill. Sputters and bogs on
straightaway. Anybody...give me a
viable answer. I am losing money cuz I
can't work without it.

17 Answers


Sounds like a vacuum leak, snug up the intake manifold, look for bad vacuum lines, PCV Valve, & EGR Valve and system components.

Best Answer Mark helpful

Faulty ground connection somewhere in your instrument panel causing a loss of power, or a dead short causing a cyclic loss of power to either the IAC or the injector circuits, especially under load...... Just my suggestion...... Cheap fix, but one of the worst headaches you can possibly get..... If you own a car and have to sometimes work on it yourself, buy a Chilton's or Haynes manual for it. Either at O'Reilly's or Autozone. Make certain you get the one that includes your own vehicle in it.

1 people found this helpful.

Doubt it on this one there Ed.

Best Answer Mark helpful

Rowefast...that's the only answer I haven't heard. Thanks I will check thatvout


I'm including a scanned copy of the wiring diagram from my Chilton's manual, colorized and a little bit modified for myself. .....Notice how every one of the symptoms described by anyone in relation to this same problem can be caused by an incorrect signal coming from the cluster to the ECM. I haven't yet gotten around to locating my ground because I've been busy modifying the diagrams to enable me to better understand them...... In "my" case there are multiple incorrect readings in the gages. I think I'm justified in at least checking out that possibility before shelling out any more money on guess work......Especially in consideration of the clear fact that everyone's guess on the solution thus far has "NOT BEEN CORRECT." And you can well believe that I have tried at least 90 percent of them, and none of them worked. Maybe I'm wrong. I'm certainly not a mechanic. But damn if I don't believe that I'm learning to be one. As much work as I've done on this truck, when I "thought" that a good mechanic who I was going to be helping change the block out and all the rest of the junk that wound up getting done. He liked to disappear, when I had no idea in hades what I was doing...... Except for that manual, which helped me, except in a couple of things that I could complain about, but it wouldn't do me any good to complain, cause Chilton's wouldn't listen. I need to get off this and go pull that dash to see whether or not I'm full of crap about my, and it is, unprofessional guess.


Today I checked and double checked everything. Each time, clearing codes from PCM. Found my evap line to engine not even connected at canister. So everything back in place...pcv cleaned and rattles just nicely. Start engine...go down Street 200 feet...start having a case of constipated diarrhea, puking at the hill, and coughing like a dying old lady what smokes three packs a day. Idles nice in the driveway.


Thinking it is running out of gas. What about the fuel pressure regulator? I see you replaced the fuel pump.


You may also want to do a fuel pressure bleed down test.

1 people found this helpful.

Came with new one...clear and clean. But the bleed down...that is easy one. On the rail where I did pressure check. Does engine need to be running during bleed down?


No, the engine not running, just hook up the fuel pressure gauge, cycle the key to build up the pressure, key off, watch the gauge from the highest pressure reading, pressure should not drop more that 5 lbs. in 3 minutes. So what was your fuel pressure reading at idle?


Going to buy new pressure test kit today. Upon inspection of this one...found it has plugged check valve. Also occurred to me that collapsed or broken valve springs on one or both heads could cause the same symptoms. Going to remove valve covers and do some exploring. I noticed a clicking noise on passenger side of engine. At first I thought was air conditioning clutch. Removed clutch relay, air conditioner fuse, and disconnected sensor for relay. Clicking still there. Also looking into manifold temp sensor since it runs great for a few minutes then begins it's quarrle with me and my destination. Wish me luck...thanks Rowefast. I will let you know what I found.


Lots of luck since it is a Dodge...lol


Okay...new tester...Bosch...multi tester for cylinder compression as well. Goes up to 300 psi. 44 psi just keyed on. Idle 3 lb loss. Holds both pressure ranges and doesn't change but maybe 1 psi fluctuation at half throttle. Slight buildup when shut down. Maybe 2 psi. Ford mite have a better idea. Lol....have a chance to get 94 f250 King cab LB 4×4...351 cid auto for $750.00 163,000mi. Owner says tranny starting to slip. A new tranny in this town ...no problem.


Could just be torqued converter on that. I can get those online for $100.


So far the fuel pressure is sounding good. How much did the gauge drop in 3 minutes when you turned the key off? And Yes, that trany would be shot in that Ford, And if that is the 351M400 engine, That is gonna be shot as well!


Pressure only dropped about 2 points


Well crap...Thats good....I'll have to read all this again and sleep on it.

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