fuel pump or regulator problem????

Well, this is an ongoing diagnosis??? i finally got a fuel pressure gauge and am trying to figure out why she starts hard after sitting. WHen i put the gauge on the jeep had almost no pressure in the line. So i turned the key and pressure went up to like 20. the it turned over at about 28 and started and ran at about 28. i unhooked the regulator vac line and there was no change in the pressure. So, any idea if i have a problem with anything? or which part it may be? Thanks

Hard starts or long cranking can be many things or a combination of things. Try turning the key to run and then bleeding a little fuel out of the valve into a jar, then starting. There may be some air in the fuel rail.
A slightly weak battery will turn it over a bit slower (most noticeable when it's cold out) and also cause hard starts. Try it with a jump and see what happens.
A flaky CPS, will also cause long starts.
Spark plug cables and normal tune up stuff will also add to the problem.
A sticky IAC can also cause problems.
My hard starts were a little of all of the above, mine starts pretty good now.
Checking battery voltage can fool you, a load test is really the only way to know what the battery is actually doing.
Sounds like your regulator may be bad, it's been awhile since I tested mine (years) but I seem to remember it went up about 10 PSI with the vacuum line removed and plugged with the motor running. And if I squeezed the return line (the rubber part :laugh3: ) closed real hard with my fingers the pressure went way up.

yea, im not sure if its supposed to leak down like that or if there should still be most of the pressure left in the lines after sitting. New IAC in it and it starts fine after it starts once. Turns over fast.

It's been awhile since I messed with mine. But seem to remember a half hour test. You hook up the pressure gauge, run it up to 29 (28) PSI and let it sit for half an hour, it shouldn't go below 19 PSI.
Not Sure anymore, but seem to remember mine still being at 9 PSI the next morning. Good or bad I can't tell you, but mine starts OK for an oldy. Mine usually starts on a quick count of 4 or 5. If the battery is really cold 7 or 8.
I put in a set of solid core plug wires, which really seemed to improve the starts. When my CPS finally crapped out and I put in a new one, it also started somewhat quicker. There was a time I'd have to crank mine forever to get it going.
Most people say the main problem is, the fuel rail bleeding down through the check valves.

any other help on how to test the regulator and fuel pump?

Year and model jimmy.

this is an 89 xj 4.0

Jimminyc said:

this is an 89 xj 4.0

Click to expand...

Then your fuel pressure is to low.
Clamp off the return line back to the tank and check pressure to test regulator, you should see at least 49#.
The correct pressure need to be 31# running 39# with key on.
A broken hose in the tank or bad pump is the likely cause of your problem.

langer1 said:

Then your fuel pressure is to low.
Clamp off the return line back to the tank and check pressure to test regulator, you should see at least 49#.
The correct pressure need to be 31# running 39# with key on.
A broken hose in the tank or bad pump is the likely cause of your problem.

Click to expand...

Also, have someone else turn the key on while you have the return line clamped off, if the pressure goes to high you can pop an O-ring very quickly. If you don't have an extra person to operate the key, just clamp the line off and turn the key on for a couple seconds. If the pressure goes up to at least 31-50psi, then your regulator is stuck open and needs to be replaced. If the pressure still doesn't come up, then the fuel pump needs replacing.