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89 2.5 4cyl wont stay running, fuel?

jeeptorino68

NAXJA Forum User
Location
Lebanon OR
Hi
just got an 89 2.5 comanche, it doesnt stay running.
PO replaced the fuel pump, and i think that is part of the problem, the gauge reads past full, and he said the inside of the tank was dirty, but he never cleaned it out or changed the filter. the jeep starts...the dies, wont stay running, it is either starved of fuel or flooded, smells heavily of gas...

any ideas?
havent tried running it on starting fluid
 
Check the vacuum line at the Fuel Pressure Regulator, FPR to see if smells like gas, if yes, the FPR is bad and leaking gas into the intake and flooding it.
 
The 4.0 FPR is up front under the hood, on the driver's side with two silver colored fuel lines, steel tubing attached and one black vacuum line. The fuel line connected to it is attached to the fuel injectors above the intake manifold.

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There was very little difference between the 4 and 6 banger out side of the engine guts, a few less wires and a different ECU and a shorter bay/ engine mount area under the hood to get the shorter engine closer to the radiator.
 
1989 is Renix, not Chrysler.

TBI, not MPI.

Fuel regulator is internal, note the return line on the TBI.




Change your filter, it's on the frame rail just behind the drivers seat.
 
Interesting I thought the 2.5 L also went to MPI with Renix in 87 like the 4.0

So the in 87 the 2.5 did upgrade to renix ECU control, but stayed with TBI?

Is that you rig in the photo? You still have one running? Look nice!! Oh and welcome to NAXJA!!!!!

I had an earlier TBI 2.5 with an old style block mounted fuel pump running off the cam shaft and a hoard of vacuum operated crap all over the engine bay, I thought it was an 84, but reading up on Yucca man's site it must have been an 86?

http://www.yuccaman.com/jeep/history.html

I have an 85 2.5 L, that was converted to a diesel (Nissan SD-22 from a Nissan 1981 720 PU truck), but it still has all the old vacuum operated crap all under the hood.

I see rock auto still has parts for the TBI beasts :)

But oddly, they show MPI parts for the 89 2.5 L as well. But I trust the Yucca man site history more than I do parts house data bases. Thanks for filling us in!!!
 
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In 85 the 2.5L had the Carter YFA computer controlled carb. In 86 they went to the TBI system. I know because I converted my 85 from carb to injection. Later, I don't remember what year, they went MPI. Instead of upgrading to MPI, I built a 4.7L stroker and swapped it into my 8. Talk about a power boost.:D
 
I could have sworn the one I had for a short while was an 84 (from the title), I do know it was TBI for sure, and we bought it from the original owner, but he was not mechanic, so it must have been an 86.
 
I will start with the fuel filter and go from there. Thanks for the info so far

If the fuel pump is on the passenger side of the block running off the cam shaft, check the oil dip stick for any hint of gas odor, if you find gas in the oil, change the fuel pump and drain the oil and replace the filter because the diaphragm is ruptured and leaking gas :gag: into the oil. Yours may be in gas tank for TBI, but just to be sure.
 
Is there a fuel pressure test port on the fuel rail? Is the fuel pump in the gas tank on TBI jeeps?

1989 is Renix, not Chrysler.

TBI, not MPI.

Fuel regulator is internal, note the return line on the TBI.




Change your filter, it's on the frame rail just behind the drivers seat.
 
Fuel pump is in the tank.

There is a line in and line out, regulated and returned.

Pump runs at 15lbs. Yes, there is a 1/4" pipe thread port. When I install my new engine I will install a permanent gauge at the port.
 
Try running it on carb cleaner. Mine would idle, but it wouldn't go. A new pickup screen on the pump would last a drive. Problem was solved by replacing the fuel tank, and of course, yet another screen.

If it has good throttle response and runs okay on carb cleaner, but goes south when the spray stops, I'd eliminate that tank in short order.
 
Try running it on carb cleaner. Mine would idle, but it wouldn't go. A new pickup screen on the pump would last a drive. Problem was solved by replacing the fuel tank, and of course, yet another screen.

If it has good throttle response and runs okay on carb cleaner, but goes south when the spray stops, I'd eliminate that tank in short order.

A problem like that can be located and confirmed with a fuel pressure gauge, with out touching or dropping the gas tank.
 
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