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Slow turnover when starting?


NAXJA Member #496
NAXJA Member
Ok, heres the deal. For the last 3 weeks or so when I turn the ignition, the thing turns over like the battery barely has enough juice to crank the engine but it starts up just fine within a normal time frame that I would expect it to fire up. It doesn't matter if I just drove it for 5 hours straight or if I havn't driven it for 6 days so the battery isn't draining while parked and I put a voltmeter across the battery while running and it read 14 + volts so it's getting a charge from the alternator. Any ideas as to what the problem might be? Thanks (its a 93' 4.0)
Heres a couple of things.
1. I have a 90 xj, and i was told to turn the ignition to the on position (just before the crank position). Let the pumps regulate and set up. Then turn it to crank. This will only take maybe 1 or 2 extra seconds but it helps a little.
2. What about your starter? your jeep is now 10 years old, maybe time for a new one...maybe an HO.
Also, make sure everything is off when you crank it up, the more you have on the more juice it will try to draw out at once.
I do let the fuel pump prime before cranking as a habit due to my fuel cut off switch, sometimes I'll even double check and turn the key back OFF then back to ON before starting . Also everything is off, to my knowledge there shouldn't be any additional drain when I start....

I went through this same problem a few years back. I changed the starter, no improvement. I then changed the fuel pump, sock filter, and fuel filter and solved my problem.

My vote is for a fuel pump. Make sure you pick up a new O ring for the tank flange when you change it. If your XJ like mine you can change the fuel pump without draining the tank.

The check valve gets bad and lets the pressure bleed off. I went to the dealer and paid for the kit. It comes with a Bosch pump and for my XJ there were wires I needed to change. The factory pump had 1/8" spade terminals, the replacement had 1/4" spade terminals. They even gave you all the rubber pieces you needed to mount the new pump. Nice kit/nice price. Three years ago it was $175.


Thanks for the tips. I figured it out with a little help from my Electrical Engineer father. He was thinking it had to be the starter or something internal in the engine but advised me to do more electrical tests first. First I checked the voltage of the battery while the engine was off (should have done that before)= only 10v ah ha. Next I hooked up the jumper cables to my Fathers car and started the XJ = starter ran alot better confirming a battery issue. Then I shut it off while dad watched the voltmeter, it dropped to 13v which seemed ok. Then I turned it over without starting and voltage dropped as it cranked then only climbed back to 10v afterward.
conclusion = bad cell in the battery, since each of the 6 cells provide 2 volts. It would maintain only a 10 volt charge but was still enough juice to get the engine started.
Solution = can you say Optima!

Anybody know good place to get a deal on an optima red top?:D

xj(if it breaks, upgrade)blue