Help, Hard Start (Students XJ)

My sons 91 XJ, has developed a hard start issue. Will start and run, but once he shuts it off it will not start back up for thirty minutes.

Symptoms: Fuel smell, no back fires and no start

What we have done:

New fuel pump and Fuel Filter
New Distributor, cap , rotor and coil
New CPS
Reset timing several times, when it starts it runs fine
Swapped out spark plug wires with my XJ and still no help

I've read several post and am willing to try anything, a buddy loaned me a scanner but it doesn't have the same connection. He's put a lot of money maintaining it, its his daily driver so any suggestion would be much appreciated. Thx

how did you "reset the timing". The timing is controlled by the computer and is not adjustable. Seems to be maybe a heat-soak issue, which usually points to the Crank Position Sensor (CPS). When you replaced it, did you go with an OEM/dealer part? Have heard lota about how parts store CPS's are junk.

Why did you replace fuel pump? Low pressure? Or was that just a whim...an expensive whim!

O degrees TDC where it is now and when it runs idles fine, early we tried 5 BTDC (according to Chiltons) and didn't get results. And the fuel pump was replace a couple months ago. And CPS? Oreilys. But we tested the old and new same results .05 at crank

Well, fuel smell and no backfire indicates no spark. Did you or son check for spark when it had the no-start condition. If no spark, I'd suspect the CPS.

I still don't know how you adjust the timing...never tried, but from what I've read its not adjustable at all. How did you adjust?

Also, on next hard-to-start, try holding gas to the floor during cranking. If it starts, it was flooded...then need to chase flooding problems...

by reinstalling the dist. at different degrees. I know once it drops in its done, no adjustment. We have spark so maybe it is a flooding issue. Thx

I forget the cut off year, but if there is a fuel pressure regulator on the front of the fuel rail, check the vacuum line while running the engine, for fuel. IF there is wet fuel in the nipple or vacuum line the FPR is bad, leaking fuel, and flooding it. Also makes for a rich, sometimes rough idle. Other suspects are the MAT and CTS, temperature sensors. The change resistance with temperature, which can be tested with an ohm meter versus factory spec. The temp versus ohm tables are in many old threads here.

eddiedatorch said:

by reinstalling the dist. at different degrees. I know once it drops in its done, no adjustment. We have spark so maybe it is a flooding issue. Thx

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Be sure to set it back to factory spec!!!

We borrowed a Fuel Presser tester and tested the FPR, BAD. Replaced it, set Dist back to 0 TDC situation is improving, but that should do it. Thx Everyone.

Oh well. still not acting right, still hard start after warming up. Reluctantly, we did a "Leak Down" test, (thought we were spinning our wheels since we installed a new FPR a day ago and Fuel Pump a month ago) But the readings were low, we followed the instructions and the fuel pump didn't reach the high pressure that it should have after pinching the return line and it dropped 40 lbs after only 17 mins. Changing out Fuel pump today.