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Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3406
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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1997 dodge ram 1500: 5.2l..4X4, manual trans..backfiring

Customer Question

i have a 1997 dodge ram 1500, 5.2l. 4X4, manual trans. It started out missing and backfiring around 80 to 100 kph. Then chk eng light comes on and code for crank sensor. I install new crank, o2, tbs, and map sensors. still the same only with a added stalling when engine warmed up and clutch depressed. runs find cold. also i can't find the egr valve. its not where they say it is.
Submitted: 9 years ago.
Category: Dodge
Expert:  sunvalley brian replied 9 years ago.

The 97 wont have a egr valve. Have you had any check engine light on?

Check fuel pressure?

Intake gasket ever been replaced?

Customer: replied 9 years ago.
thks for the reply:

i did have a check engine light. at times O2, crank, tbs, and cam sensor.
but they were clear. I changed all but cam sensor because none of them made any different.
Intake gasket, i assume you mean between the intake manifold and the heads? They have ever been changed.
I don't think the fuel pressure has been checked but it is at a service station now for several days. I live in a rural area and there are not any large service centres.
Customer: replied 9 years ago.
Relist: I still need help.
Expert:  sunvalley brian replied 9 years ago.
The intake gasket i am talking about is bolted to the bottom of the intake this is a common failure on the magnum engines. Let me know if you need to know how to test it.
Customer: replied 9 years ago.
Reply to sunvalley brian's Post: how to test intake gasket?
Why does the engine stall when clutch engaged?
Expert:  Dodgerench replied 9 years ago.

Good morning,Customer

That's quite a list of problems you have with your Ram. I'll list a few questions of my own to (maybe) clarify some of the things you have going on in my imagination. Write back when you can...

  • The way I read it, you had the bucking problem first and then stalling came later. Is that right?
  • Have you had any work other than this done recently?
  • When you push the clutch and the engine stalls are you coming to a stop (foot off the accelerator) or does it instantly kill the engine as if from an electrical switch?
  • The backfiring. Is it coming from the intake or exhaust?
  • Does it backfire when going deep into the throttle or when you let off the throttle?
  • Is it a continuous backfire, or erratic in nature?
  • Is there a particular engine or vehicle speed where the backfiring occurs?
  • Let me know how deep into the throttle you are when the bucking/ backfiring happens.
  • It looks like you had codes set for all those parts you replaced, plus the cam sensor. Is that right?
  • Was it the upstream or downstream 02 that was replaced?
  • Can you list the actual codes?
  • Did you use factory parts?
  • You mentioned the engine runs fine when cold. Does that mean that neither problem shows up and that the engine runs 100% OK until warm?
  • At what temperature does it start to act up?
  • Has the distributor been turned/ adjusted lately?
  • How is your battery? Does it seem a bit weak on cold starts or require a jump start at any time?

I'll stop there for now. I have a feeling there's more than one problem at work, especially if your stalling problem happens at lift-throttle (stops, turns, etc). Try to remember the specific codes you've seen in the past and check for new ones if you can.

Sorry about the long list... but there may be more (lol)!


Customer: replied 9 years ago.
Hi dodgerench: thks for your reply. to answer your questions:
First the missing was every now and then, then more often, usually around 50 to 60 MPH if I tried to accerlate easy, it became worse at hard acc and keeping backfiring as long as i increase the gas (like its choking). from the exhaust.It started out as an O2 sensor, i replaced both up and downstream. no change in performance.
I then got a cam sensor code, replaced cam sensor. I then replaced the tps sensor and the MAP sensor. All with no change in perforance. I did get cam sensor/injector code i can't remenber actual code numbers.
All along it would stall while stopping, turns.
Battery is strong. When the engine is cold(first start or fater sitting until cool) it runs OK. When it gets to operatoring temp the problem starts. It stalls when i put the clutch in (from standing still)
If driving it will stall when i put the clutch in. I''ll hsve to jump start it while rolling.
When this first started I also changed plugs , distributor cap and rotor, no change.
I took it to service station. They says also when they put clutch in fuel pump comes on.
I assume truck with key on, nostart. Short?
I try to use factory parts?
Expert:  Dodgerench replied 9 years ago.

Thanks tosh! No surprise, but this isn't going to be easy.

Yes, more questions...

  • You mentioned earlier that the crank sensor was replaced, not the cam. These things tend to run together after a while. Just for reference, the cam sensor is in the distributor, the crank is in the front transmission bellhousing. Did you do both?
  • Was the distributor removed or turned at any time?
  • Did I read this right? If you push the clutch in while sitting still it will kill the engine?
  • If this is right, does the engine shut off suddenly as if the key was turned off?
  • Have you had the transmission or engine out recently?

I'll leave a couple of things for you to check while I'm out (might be gone for a few hours).

Slide under the truck behind the right front wheel area and give the catalytic converter a light whack with a soft mallet or the side of your fist (if the cat's cool). Listen for rattling within the housing. I'm not sure how much of your problem could be caused by an exhaust restriction, but the information is needed any way we slice it.

Check your coil wire for continuity between ends. A bad coil wire can cause some of your complaints, but not necessarily all. A good wire will show continuity when the 20K scale is used on an ohmmeter. It's not that important what the value is, just that it's within that range. The wire may fall apart at either end if it's burned out bad enough to cause driveability problems like yours...

A coil output test might be in order if you get a chance. Pull a plug wire off and insert a screwdriver into the spark plug end. Position the metal shaft near a good ground source and start the engine. You should see a minumum of 1/2" of spark leaping the gap. More is better. If it's less, let me know.

Thanks for slogging along here. I can be a real pain when it comes to information LOL!

Talk later, Ed

Customer: replied 9 years ago.
Tks Dodgerech:

I did change the crank sensor aftor a code. it made no different. I had a cam/injector code after that just once i cleared it it didn't come back.
The distributor hasn't been moved.
Yes it will kill the engine sitting still but it is choking and missing before it dies. If I tried to keep it going i can hearing tappets and valves knocking before it spudders out. Catalytic convertor ok. No resrictions, in fact, late last fall brfore this started, i installed new catback exhaust system from summit racing
.I'll have to check the coil later. never had the engine or trans out.
I had the truck for several years, great working truck, never abused or used off road. always well maintained.
Expert:  Dodgerench replied 9 years ago.

Your comment about the guys at the service station telling you the fuel pump comes on when you push the clutch in makes me wonder if you're losing fuel pressure.

There's no direct link between the clutch and your fuel pump, but it sounds like there might be a relationship somewhere there.

Backfiring and running worse as the throttle is pushed harder also fits loss of fuel pressure, as the noise you describe before the engine dies. A hot engine will pre-ignite and rattle as it becomes so lean that it can barely run. The noise you hear might be the engine finishing up its last little bit of fuel pressure.

The heat from a fully-warmed up engine will keep the engine running a little longer after the fuel pump stops. It causes the fuel in the injector rail to boil as pressure is lost. The vapor produced by boiling temporarily props up fuel system pressure and keeps the engine running a little longer, albeit poorly.

I don't see the direct link to the clutch yet. There might not be one. But wiring in the steering column area isn't far from the clutch linkage. Do a little look-see under there to see if something might be loose or coming into contact with either your left foot or the clutch linkage. You might have the engine running while you wiggle as a piece of positive feedback if you find the right spot.

Same thing underhood. Do a little wiggle testing of the harness in the left front wheel area and below the power distribution center. Fuel pump power travels down that section of harness that you can see below the brake booster and goes through a pair of connectors.

This is beginning to sound enough like a fuel pump power supply problem that it might be worth hot-wiring the pump so you can leave the engine off and just listen to the pump as it runs.

Remove the fuel pump relay and jumper between the #30 and #87 terminals (marked on the relay underside). This will run the pump continuously with the key off. In case I'm wrong on the numbering... jumper the two terminals that are turned opposite directions that are directly opposite one another. Three terminals face one way, one turns another. Jumper the odd one to the one straight across from it.


Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3406
Experience: 30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
Dodgerench and other Dodge Specialists are ready to help you
Customer: replied 9 years ago.
thanks ed: I'll have to wait until monday as the truck is at the service station
Expert:  Dodgerench replied 9 years ago.

It's all good Bernie. We'll talk later.

Enjoy your weekend!


Customer: replied 9 years ago.
Reply to Dodgerench's Post: ed
I asked at the service station to do a pressure check on the fuel system. They said since the truck didn't have a valve for testing and they didn.t have anything to test it with.
I'll have to take the truck elsewhere or rig something up myself.
I let you know.
i ready appreicate all time effort you are putting into this problem
thank you
Expert:  Dodgerench replied 9 years ago.

They're right, Bernie. Your year was the only one with a plastic fuel rail and it didn't come with a test port (dang!). You have to use a special adapter and I doubt they would have one.

Don't try to improvise ... those rails are a little delicate and replacement is expensive. We might be able to work around it for now.


Customer: replied 9 years ago.
i picked up thtruck from the service station today. it started great and ran well home, about 4 miles. i stopped at the top of my driveway pit the clutch in and it cut out. i hot-wired the fuel relay as per your instructions. fuel pump ran continously. so, i started the truck ran, rpms fluckuated somewhat, but didn't stall. drove into driveway about 150 yards. this was better. what does it mean, regulator and/or pump.
Expert:  Dodgerench replied 9 years ago.

It might mean that you just have a bad fuel pump relay. Or it could be a coincidence. Tough call.

You could try another relay from the PDC in the place of the fuel pump relay. They're all the same, so take one from something that's not real important, like an A/C compressor clutch relay. Check out the terminals in the PDC to see if there might be some signs of heating or plastic damage from heat.

Since you seem to have seen positive results from jumpering the output circuits to the pump, I wonder if there might be a problem with the control side. The PCM grounds the relay to operate it... maybe there's something wrong with the control circuit. The next time you feel the engine losing power, pull the fuel pump relay and listen/ feel for a click as you make and break contact. The fuel pump relay control should be grounded to energize the relay any time the engine is turning.

If all else fails, hotwire the fuel pump relay and see if the engine will run indefinitely like that. I don't recommend you drive it this way, since there would be no way to stop the fuel pump from running in the event of an accident. But if you think it would act up sitting in the driveway, jumper those two terminals.

Just curious... how much gas is in the tank?


Customer: replied 9 years ago.
There about 1/3 tank of gas at the moment but I usually keep it 1/2 to full. It all sounds good I'LL let you know in a few days now it goes.
thank you so very much for your help
Expert:  Dodgerench replied 9 years ago.

Thanks Bernie. The reason I asked was that the inlet filters to the fuel pump module can become blocked on these units if they're the paper type. Fuel levels above 1/2 allow fuel to slosh into the pump module reservoir, bypassing the filter at the base. If you're running out of things to try, put some extra gas in the tank. If it immediately runs better, we might be just looking at a new inlet filter.

Keep up the good work! Talk later,


Customer: replied 9 years ago.
Hi dodgerench:
I'am back!
OK here's the scoop. I solved the issue with the truck stalling when i put the clutch in. it was the engine coolant temp sensor. My niece's husband had the same problem with his chev. trk. Still missing on warm up at 2000 to 3000 rpms. i have to upshift to drop the rpms to stop the missing(bucking). I got a code P0256 (injector pump metering control B, (cam/rotor/ injector. What does that mean?
I installed new wires, still the same. No code yet! I hotwired the fuel pump and installed pressure tester on fuel rail. discontected from furl rail, truck not running, got fuel pressure of 48 psi. Good I think? still missing(bucking). any ideas left?
So to date changed plugs, wires, distributer, rotor. Changed Crank, tps, Map, Upper and lower O2 sensors, and eng coolant temp sensor. Did I miss anything?
So what does code P0256 mean exactly?
Any ideas.
Expert:  ProAnswerMan replied 9 years ago.


I have run into a similar condition on several BR trucks and I think the misfiring g and the back firing not setting fault codes. Remove the fuel rail from the engine , put on clean work bench with a cloth under it (white). Remove each injector , one at a time and inspect them for rust or dirt in the ends of the injector.

If you find rust or dirt in the injectors, you will need to replace the fuel rail and all 8 injectors.

Hope this helps. Just reading your history. Thanks, David

Expert:  Dodgerench replied 9 years ago.

Good work, Bernie! The coolant temp sensor isn't something I'd have suspected when the engine starts OK cold, but results don't lie.

I can't find this P0256 code. Probably because it's a diesel code of some sort. I can't explain that one... unless the code reader isn't compatible with your truck. When the scan tool and the vehicle don't connect odd codes like this can pop up sometimes. Don't worry about this one; it probably isn't real.

David brought up a valid point. If you can pretty much verify that you have fuel pressure when the engine is acting up, it just might be a problem with rust collection in the injector pickup screens. It's not iron oxide rust, but some sort of stainless steel reactant. It's uncommon but does happen.

The source is your fuel pump (if it's not magnetic). Fuel passes through a filter/ regulator assembly in the top of the pump assembly that's built of some sort of stainless steel (or similar) material. The stuff we're talking about is shed from the inner walls of the filter/ regulator can and it happens AFTER the filter media, so there's nothing to stop it from heading up to the engine.

Verification goes like David said... remove the rail and tap out the injector screens to see what falls out.

The one thing that bothers me about this is that you have a 4-mile honeymoon each time you start the truck where it runs OK. Restricted filter screens usually STAY restricted and cause the engine to run worse when cold. Tough call, especially with the plastic fuel rail...

Since you've already mastered the art of hotwiring the fuel pump, maybe a fuel volume test would be in order. Get yourself a 5-gallon can, a lenth of 3/8" fuel line and a fire extinguisher LOL. No, really get the extinguisher. Gas is dangerous stuff.

Jumpering on the same side of the truck as where you will be dispensing fuel puts these two components too close together for comfort. Be very careful to avoid stray sparks when liquid fuel is present from fuel line disconnection. Let the fuel evaporate if possbile before firing up the pump.

Then just run the pump and let the fuel fill the gas can. Time the process and watch the fuel flow to see if it markedly peters out after a short while.

Be sure the gas can is clean inside so that any particulates you may accumulate can be blamed on the correct source... your fuel system.

One disclaimer... Some fuel pump modules just naturally pick up fuel poorly at fuel levels below 1/2. You may have to add fuel to get it to 3/4 for this test to be meaningful if it begins sputtering at the discharge hose after 20 seconds.

Last, I thank David (ProAnswerMan) for his interest!

Talk later, Ed

Customer: replied 9 years ago.
i'll let you know how things go
Expert:  Dodgerench replied 9 years ago.

Thanks Bernie. Good luck!