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Steve, Auto Service Technician
Category: Car
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Experience:  25+ yrs experience as a professional working technician; ASE L1 master technician
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96 Dodge Ram 1500: liter engine..runs fine..it just acts like it..sits

Customer Question

My 96 Dodge Ram 1500 5.2 liter engine with 133K miles runs fine but someitmes it just acts like it has ran out of fuel. Truck will run (idle) but has no power to even pull itself. After it sits it will run fine until the next time. DTC code says 43. Do I need to change the coil?
Submitted: 11 years ago.
Category: Car
Expert:  Steve replied 11 years ago.

The definition of a code 42 is a multiple cylinder misfire; this could be a coil, but I have never actually seen a coil cause this condition.


The most common cause of this condition on these models is rust in the fuel rail, restricting fuel flow to the injectors. This can hapopen intermittently, and can affect different cylinders at different times although the ones most often affected are the ones in the rear of the engine. You can easily check for this problem by removing the fuel rail and dumping out the contents into a clean rag.


Also, if the plug wires are old, they could be causing the problem you describe; secondary ignition misfires usually occur under load, although the engine may idle OK.

Expert:  Steve replied 11 years ago.
Customer: replied 11 years ago.
Reply to Steve7654's Post: Mine is DTC 43. The plug wires are original wires. They have never been touched. Sometimes the truck can be off for just 5 minutes and it will start up then run fine. Which of the two would you lean towards.
Expert:  Steve replied 11 years ago.

Another thing you may want to check for on this vehicle (although it may be a result of the misfire condition, not the root cause) would be to check for a damaged catalytic converter causing an exhaust restriction; this will cause exactly the sort of power loss above idle that you describe. Hit the converter with a rubber mallot, or shale the pipe; if you can hear anything rattling around internally, it is most likely pieces of broken ceramic damaged by overheating from teh raw fuel going down teh exhaust pipe during the misfire condition. For some reason, CAT failures are very common on these trucks, and the converters are often on backorder at the dealer.


An easy way to test for an exhaust restriction is to connect a vacuum gauge to the engine, and measure engine vacuum. If the exhaust is plugged, when you rev the engine above idle you will see the needle on the gauge fall steadily towards zero.

Expert:  Steve replied 11 years ago.

seing how the truck runs fine after sitting, i would look at the CAT first; as the exhaust backpressure bleeds odff, or if the chunks move around, the problem will go away for a while.


The CAT is probably not the root cause though, if it is failed you need to find out what caused the failure (misfire?) so that it does not recur when a new one is installed.

Customer: replied 11 years ago.
Reply to Steve7654's Post: when I say power loss I mean the vehicle can't even move itself. It sounds like popping/backfire if you push the throttle down too far.
Customer: replied 11 years ago.
Reply to Steve7654's Post: it died on me the other day and I thought I was out of gas. I took the gas cap off and poured gas in and then it started backup and ran fine. But it wasn't out of gas. That is how fast it can change. Or it might have to sit for 30 minutes.
Expert:  Steve replied 11 years ago.
I would suggest a fuel pressure test if you believe it may be running out of fuel. It is at the right age for a fuel pump or fuel pump relay failure; the only way to tell would be to check the fuel pressure when the problem is occurring to see if it is below specs...
Expert:  Steve replied 11 years ago.




NOTE: The fuel pressure test port is located on the end of the fuel rail near the engine thermostat housing. A sealing cap is screwed onto the test port.

FUEL PRESSURE REGULATOR
All fuel systems are equipped with a fuel tank module mounted, combination fuel filter/fuel pressure regulator. The fuel pressure regulator is not controlled by engine vacuum.

With engine at idle speed, system fuel pressure should be 339 kPa +/- 34 kPa (49.2 psi +/- 5 psi) .

WARNING: Do not allow fuel to spill onto the engine intake or exhaust manifolds. Place shop towels under and around the pressure port to absorb fuel.

WARNING: Wear proper eye protection when testing fuel system pressure.



  1. Remove the protective cap at the fuel rail test port. Connect the 0-414 kPa (0-60 psi) fuel pressure gauge (from gauge set 5069) to the test port pressure fitting on the fuel rail.
  2. Start the engine and note pressure gauge reading. Fuel pressure should be 339 kPa +/- 34 kPa (49.2 psi +/- 5 psi) at idle.
  3. If pressure is at 0 psi, connect DRB scan tool and refer to Powertrain Control Module.
  4. If operating pressure is above 54.2 psi , fuel pump is OK but fuel pressure regulator is defective. Fuel pressure regulator is not serviced separately. Replace fuel pump module assembly.









Steve, Auto Service Technician
Category: Car
Satisfied Customers: 5494
Experience: 25+ yrs experience as a professional working technician; ASE L1 master technician
Steve and 5 other Car Specialists are ready to help you
Customer: replied 11 years ago.
hard to catch it doing it. My book saya a code 43 is ignition coil problem
Customer: replied 11 years ago.
Reply to Steve7654's Post: do fuel pumps stop and start or pump just enough fuel to keep it idleing?
Customer: replied 11 years ago.
Reply to Steve7654's Post: Does anyone else there have an opinion on this matter?
Expert:  Tech501 replied 11 years ago.
The way the fuel pump works is it pumps constantly. The regulator is a by pass type control and it returns the unused fuel tp the tank. Yes, you problem could very well be a coil. a coils will act just like that when it has reached it's KV limit.
Customer: replied 11 years ago.
Reply to Tech501's Post: The tech earlier said he didn't think so. My book says DTC 43 is a ignition coil problem. Do you know the history of our earlier conversation with other tech?
Expert:  Tech501 replied 11 years ago.

Yes, I am familiar with the prior answers. This excerpt should explain the problem


Quote:

The definition of a code 42 is a multiple cylinder misfire; this could be a coil, but I have never actually seen a coil cause this condition.


He was chasing the wrong code. You are correct, 43 is for a coil issue. Although there are no gaurantees on the coil being the prooblem, it is the most likely cause.


Customer: replied 11 years ago.
I change the coil but did not help. Thought maybe the coil wire. Do you thinkit coulf be the fuel pump even though the code says (dtc 43) coil problems?

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