I have a 1995 Dakota 3.9L with a 5 speed 2 wheel drive with 247,000 miles on it. About three months ago, I noticed it getting sluggish when starting at a stop and going up a hill. No issues if you eased into it, but only when you floored it. This my son's school truck and I don't drive it anymore. My Son told me it wasn't running correctly this weekend.

The truck idols ok and it doesn't seem to have any issues in 1st or 2nd gear. The truck really starts jerking and acts like its 1/2 way missing and wanting to backfire. Once you get to speed it seems to be ok, when you back off the gas. If you down shift it runs smoother....3.21 rear end. It runs better at RPM's over 3000.

At first I thought it was a fuel injector, so I poured 3 ozs on seaform in the vacaum line coming off the master brake housing. That didn't seem to help cleaning the fuel injectors. It really seems like its a lack of gas issue. I talked to local mechanic and he said it sound more like an electric issue. So I just replaced the plugs, plug wires, distributor cap and rotator cap. I didn't see any change in the way it runs. I'm back to square one, maybe a bad fuel injector?

My check engine light isn't on. I did a manual check for an error codes it is reading 55...no codes found.

I had replaced the fuel pump about 10 years ago. I can't seem to find and fuel line filter on the frame. I'm confused about that , does it really have a fuel filter? Some threads say yes on the drivers side of the frame and some say in the fuel tank.

Anyone want to take a stab on what is wrong with it and what to try next?

I really appreciate it,

Shane Roberts

 

Docs show that 1995 Dak 3.9 has a inlet fuel filter in the tank itself (it looks like a teabag on the bottom of the fuel pump module), and a combo pressure regulator/fuel filter externally on top of the pump.
(The factory parts list shows a frame mounted inline fuel filter ONLY for the 2.5 litre engine)

Earlier models, like my 1990, have a filter in the tank and and inline one on the driver side frame rail fuel line in front of the fuel tank.

The truck idles fine and is ok at a stable speed, but has problems on acceleration ?
Does it accelerate ok in neutral ?

 

At 247,000 miles, you might have worn cylinders/rings and might be losing compression.

What you describe sounds similar to when my Dak failed smog shortly before I pulled the v6 engine and put in the eight. I had uneven compression and very low compression on the #1 cinder.

You're going to want to check
1) timing (is the dizzy indexed properly?)
2) spark plugs gapped properly?
3) fuel system is not clogged, injectors work good, fuel system, pressure is good?
4) egr system works properly?
5) no vacuum leaks?

 

I'd be looking for an intake manifold leak, myself. Idles ok, sluggish under load, eases up when you back off? Sounds like it's pulling in air at certain engine speeds. Without seeing your truck, that's just a guess, of course.

 

Thanks for the input and here is the latest. I still have no improve. My spark plugs are gapped at .35 I just installed Autolites 3924. I checked all the cylinders today and compression is running 120(+5/-5). I installed a new gasket between the carburetor and the air filter.

The engine seems to run perfect in neutral. It only acts up under a load and at low RPMs. The vacuum lines appear to look good. If the timming is off would it run ruff while in neutral racing the engine....seems ok to 3500 RPMs? The truck never smokes or burns oil.

The truck isn't driverable at this point, and acceleration up a hill is the major problem. Once you get up to speed it seems to be better, but still has issues. The truck drivers really jerky....has power no moment and then acts like its missing.

Rambler not sure what to look for on the intake manifold and don't what the EGR system is.

Thanks everyone for taking the time to help me out.

Shane

 

I should have said intake manifold GASKET leak, sorry.

Here's the EGR valve.

 

Timing chain is stretched. Chains are rated for 60-80k miles and often last much longer. But 240k? No way. A new chain will work wonders. Until then you're smearing lipstick on a pig.
While doing the timing chain, its an opportunity to replace the water pump and radiator. They would be due at this point if not recently replaced. Its more likely you have a throttle body, not a carburetor.
Let us be real, at 240k, some serious maintenance is due.

 

 

Removed

 

The video description lists the problem: the fuel pressure regulator.

If you have the returnless system, and by '95 you do, the regulator is in the tank, so it's as much fun as a pump replacement!