Bad Fuel Pump?

I've been having a really bad surging problem. No one can figure it out. Yesterday morning my jeep wouldn't start. It would actually start and die. I didn't hear the fuel pump come on at all, so I thought that's why it's not starting. After work, I tried it again, and it started right up and the fuel pump was running. So, my question is, if the fuel pump is going bad, then can that cause the engine to surge?

It could be the problem. Try to check the pressure at the rail.

Starting and dieing is often a sign of a bad ballast resistor, jump it for a test.
Sometimes it's a sticky IAC. It can also be a sign of a bad sensor someplace.

It's running right now. The IAC has been cleaned. Every sensor on it has been checked. The grounds have been checked and rechecked. No one can find anything wrong with it. If the ballast resistor is bad, could that cause the fuel pump not to run?

my suggestion is to replace the fuel pump relay I had the same problem and found the relay not making good contact all the time making the fuel pump cutout or sometimes not even start. It's cheaper then throwing a fuel pump at it and yes check your ballast resistor.

Yes, an open ballast resistor will cut power to the fuel pump. I believe that resistor is bypassed during "start", then is placed into the circuit when the key is released; so it would be possible for the engine to fire, the immmediately stall.
I don't beleive the resistor would be intermittent; other than a loose connection, the resistor is generally good, or bad.
If turning on the key (but no start) doesn't cause the pump to run for 2-3 seconds, check all electrical, including the fuel pump relay, wiring and connectors at the fuel tank, and lastly, the fuel pump.

Kreutz said:

I've been having a really bad surging problem. No one can figure it out. Yesterday morning my jeep wouldn't start. It would actually start and die. I didn't hear the fuel pump come on at all, so I thought that's why it's not starting. After work, I tried it again, and it started right up and the fuel pump was running. So, my question is, if the fuel pump is going bad, then can that cause the engine to surge?

Click to expand...

what year, it might not have the ballast resistor

Kreutz said:

It's running right now. The IAC has been cleaned. Every sensor on it has been checked. The grounds have been checked and rechecked. No one can find anything wrong with it. If the ballast resistor is bad, could that cause the fuel pump not to run?

Click to expand...

During start the ballast resistor is bypassed, the current to the pump only goes through it when the key is in run position. May also be the fuel pump relay, but they rarely fail. The relay block does get full of mud and corrosion though, a possible trouble spot.
The easiest way to find out is too stick the two spade connectors (on the wires) together (tape them up) at the ballast resistor and try it out. Jumping the ballast resistor won't hurt anything.
I snipped one spade connector off of the wire at the ballast resistor and crimped (and soldered) on a combo male female spade connector. This makes jumping it for a test easy and may also come in handy by the roadside someday.
On my 88 the back of the ballast resistor was blown off (where It couldn't be seen) I guess from heat and splashing it with water. My fuel pump function got iffy. It would always start fine, but would sometimes run lean during highway operation. Acted like I was running out of gas.
It did almost the same thing once when my O2 sensor was going out, but it was most noticeable at a round 2000 RPM +/-, why I can't really say, but my best guess was the O2 sensor tended to act up more during high vacuum conditions.

It's a '90. I think I've replaced the ballast resistor a couple of years ago, but I'll go ahead and get another and check the fuel relay and all connections.

check fuel pressure at the rail with a gauge.

test the ballast for continuity and resistance, i believe 1.6 ohms.

I've got a 1992 that won't start, I think I've got a similar problem. No voltage to fuel pump, when I connect 12V directly to pump, it runs. Changed ballast resistor, did not fix. Swapped fuel pump relay with another in PDC, did not fix. If I connect battery directly to green/black wire (input to ballast resistor according to wiring diagram) fuel pump runs.

I'm trying to understand how the ballast resistor is bypassed during start. The purpose of the ballast resistor is to reduce voltage to around 6V, correct? The wiring diagram on page 12-22 of the Haynes manual shows 2 fuel pump relays and 2 ballast resistor relays. The relays are identified, but location (like inside PDC) isn't listed. The owners manual shows one fuel pump relay in PDC, which one is this? The one that bypasses the ballast resistor or the one that supplies voltage to it? Where are the damn ballast resistor relays?

I'm about to go NASCAR and wire in a switch directly from the battery to the ballast resistor.

I can also be reached at [email protected]

Thanks,
David

bad cps will stop voltage to pump.

thanks, will check