Hi,

My 1988 Dodge Dakota will start, but then immediately stall. It seems as if as soon as the engine starts, something seems to cut off the fuel pump. The truck will run with fuel poured into the throttle body.

I removed the fuel line from the throttle body and cranked the engine, and fuel came out of the line, so it appears the fuel pump is working, and it should considering I recently replaced the fuel filter and fuel pump/sending unit assembly.

Last night I removed the ignition switch, and it appears to be functional, but I'm ordering a replacement to test.

I'm not receiving any codes from the computer.

Despite being a fuel-related issue, I've replaced the distributor cap, distributor rotor, distributor pickup, spark plug wires, and spark plugs.

Does anyone have any idea what would cause the fuel pump to shut off? This has me stumped.


Thanks in advance.

 

Do a fuel pressure test. Put a T on the inlet (surprise, it's the lower one of the two!) and make sure you've got 14.5psi.

If it's much over 14.5PSI, the injectors can't lift so you won't get fuel.

If it's much UNDER, you've got no fuel to keep the truck running.

It could be as easy as there's a blockage in the lines to the TBI, or the regulator is bad.

And having fuel doesn't mean you've got sufficient pressure; deadhead it should be over 45PSI (some folks have reported over 100PSI when the pump's deadheaded.)

RwP

 

Thanks for the information, Ralph.

I just finished testing the pressure and got a result of 70 PSI.

Looks like I need a new fuel pressure regulator!


Fuel Pressure Test

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That's only a little bit high.......

 

Yah. As soon as the pump pressurizes, the poor injector just gives up the ghost.

Ideal is 14.5PSI on the TBI motors, so ...

It's like opening a door out with almost 5 atmospheres of pressure on the other side!

RwP

 

I got the new fuel pressure regulator in the mail today.

I swapped out the old regulator for the new one and attempted to start the truck, and found that the battery was dead. In that case, I got my trickle charger out, connected it to the battery, and set it to 100A and jump started the truck.

After jump starting the truck, it started right up and ran, but after a short period, it stalled and is back to starting up, then immediately stalling. This appears to be a new, computer-related issue.

Normally, when I'd turn the key to the 'on' position, the check engine light would come on and then soon turn off, and I also had the ability to do the 'on-off-on-off-on' sequence to read codes from the compute, but now, I can't get either of these things to happen.

I removed both terminals from the battery for what I estimate to have been about an hour in an attempt to reset the computer. After reconnecting the terminals, there was no difference.

Any ideas?

 

Let the battery charge overnight.

A flaky battery makes our ECUs go downright nuts; before I blamed anything else, I'd do an overnight 10A or 2A charge, and see what it's doing.

Also, I'd be checking the output of the alternator - dead heading into a dead battery will kill most of today's alternators, alas.

RwP

 

Idle motor may be on it's way out, Charge the battery start the truck but keep you foot on the gas and see if it stays running.

 

Charging the battery overnight did the trick for the engine computer and it is now working properly.

As far as the stalling issue goes, I undid the return line, grabbed a bucket for the fuel to drain in and started the truck. Ran perfectly.

I reconnected the line after some fuel came out and the truck runs! I'm not entirely sure what the deal was, maybe something clogging the line or trapped air in the line.


Thanks for all your help!