Yesterday morning I was driving down the highway moving right along with traffic, as traffic slowed and came to a stop my truck decided to stop too. Truck stalled in middle of 4 lane highway and would not start again, ended up having to be towed. Any ideas why this may have happened? I have fuel air and spark. Replaced the coil and tps(broke when i was trying to get to distributor) truck now runs ok. I am thinking my fuel pump may be dying as was not alot of pressure in fuel rail... gonna test with guage tonight. Any suggestions?

 

+ on the fuel pump. Mine did the same thing, when the FP was on it's way out.

 

Depending on when you measured, it is NORMAL for the pressure to read 0 psi.

You'll want to measure the psi at the rails when it's running and, after. Spec is 49 psi ± 5 psi. ON the older Ram model such as a 94, spec is 36 psi ± 5.

What your going to look for is one or more of the following:

-bouncing reading

-sudden drop in pressure and then returns to normal

-sudden rise in pressure and then returns to normal

-steady, low pressure (below specs)

There's also another system that can also create the same symptom and that is the Emissions system.

-EVAP canister - has been reported to induce stall out under certain conditions.

One other thing to check:

COIL: Intermittent coil either from two possible causes:

1. LOSS of voltage to INPUT of coil- ASD relay is going out or,

2. LOSS of ground to the coil connector
2.1 PCM coil driver CKT is intermittent thus not switching on ground
2.2 Loose / intermittent ground connection at PCM multi pin or connector
2.3 Loose / intermittent connection at coil connector / corrosion

OTHER POSSIBLE CAUSES:

Complete Loss of Power: ASD relay- may have gone south and went OPEN CKT thus, no power at all to the EFI system including ignition and fuel pump.

Failure / Intermittent FUEL PUMP relay.

Start there.

CM

 

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thanks guys really appreciate the information I will fill out profile to as what truck is now, my computer died previously.

 

Ran codes found upstream o2 to be tripping ASD, replaced sensor and ran better but still not how it should be, still stalls randomly but will restart 9 out of 10 times... if only cranks i can pull and put back ASD relay and will fire over again without issue... I am lost at this point

 

"stalls" like at low rpms......check iac

 

Next time it happens, try swapping the ASD relay for one just like it (I think there are at least 2 others) and see if that makes a difference. Could be the relay starting to go bad and not latching properly.

 

I believe the reason why it will start after PULLING the ASD relay is; when pulling that, power to the PCM is cut thus wiping out the RAM / clearing it thus allowing it to start every time - UNTIL the code is generated again to which it executes the Automatic Shutdown Command failsafe mechanism.

I know the O2 sensor supply is tied off the ASD but, I will have to research that comment about it tripping the failsafe mechanism- to my knowledge, I don't think that it does. Hell, you can pull it out and it will still run. Some have even disconnected it completely and it still ran so, the only way that I can see it tripping the ASD relay is if the O2 sensor were SHORTING inside.

A SHORT on that side would be seen at the PCM level and it would cut all power to the ASD relay.

R&R your O2 sensor and re TEST. Recommendation: Use the OEM recommended NTK brand of O2 sensors vs. Bosch. WHY?

I have had issues with Bosch sensors and plugs over periods of time that were way under the rated use life. Since going back NTK I have yet to experience a failure. Plus, if I am not mistaken, the NTK also have a higher tolerance to heat and are less prone to clogging than Bosch's too.

CM