New issue- 90 Cherokee
#1
New issue- 90 Cherokee
First off, thanks to cruiser54 for all the help I was having the past couple weeks. Put the spare fuel pump in and it ran like a champ... For 3 days... I blame the wife... LOL
New "issue". I drove to work and back this morning, waited for the wife to get home from work, then we began the drive to the store. Never made it. About a third of the way there, we turn a corner, and the wife says "wow, it really is running better"... After making the next turn (less than half a mile later) it just shuts off. See previous comment from wife... I blame her. I notice I can't hear the pump. So I pull into a parking lot, turn the key off and back on, still no pump noise- but when I try to start it, the pump kicks on and it starts fine. I'll drive a little bit (anywhere from 100 feet to a mile and a half or so) and the pump will stop and the restart process starts again. The pump relay is clicking when I turn the key, so I'm thinking the pump sat for too long and is cutting out. My meter and all of my tools are at work, so I won't be able to do any in depth diag until Monday, so my question is this- are there any known issues with certain parts that would cause this and maybe cut out some digging when I get it to work Monday? Any thought or suggestions (no, I'm not selling it like the wife wants me to do... LOL)? I was even considering doing some custom wiring and running the pump through a switch to be turned on and off (think a fuel cut-off switch/theft deterrent), but I'd have to check the schematics (which are also at work ) to see if it was do-able.
New "issue". I drove to work and back this morning, waited for the wife to get home from work, then we began the drive to the store. Never made it. About a third of the way there, we turn a corner, and the wife says "wow, it really is running better"... After making the next turn (less than half a mile later) it just shuts off. See previous comment from wife... I blame her. I notice I can't hear the pump. So I pull into a parking lot, turn the key off and back on, still no pump noise- but when I try to start it, the pump kicks on and it starts fine. I'll drive a little bit (anywhere from 100 feet to a mile and a half or so) and the pump will stop and the restart process starts again. The pump relay is clicking when I turn the key, so I'm thinking the pump sat for too long and is cutting out. My meter and all of my tools are at work, so I won't be able to do any in depth diag until Monday, so my question is this- are there any known issues with certain parts that would cause this and maybe cut out some digging when I get it to work Monday? Any thought or suggestions (no, I'm not selling it like the wife wants me to do... LOL)? I was even considering doing some custom wiring and running the pump through a switch to be turned on and off (think a fuel cut-off switch/theft deterrent), but I'd have to check the schematics (which are also at work ) to see if it was do-able.
#3
Nope- never made it that far. Just for sh@ts and giggles I checked the fuel pressure when it was running (the ONLY tool I have with me) and it was still pushing 32 psi. The pisser is I couldn't get it to cut out while idling, but when I was driving, I could hear the pump cut out. At least I had a little warning so I could get off the road or into a parking lot.
And correct me if I'm wrong, but the ballast resistor is on the inner fender by the air filter housing, right? Might by-pass that and see what happens (again, for s and g's...).
And correct me if I'm wrong, but the ballast resistor is on the inner fender by the air filter housing, right? Might by-pass that and see what happens (again, for s and g's...).
#5
Not sure- it was the pump I took out when the sending unit puked out. I put a sending unit in I got off e-bay and it had the pump in it already, so I just kept the old pump "just in case". I already figure I'm going to have to put a new pump in (figures, since I JUST filled the tank about 4 hours before this happened ), I just wanted to know if there were any other known issues to check...
#6
It's only there to reduce fuel pump noise by lowering the voltage slightly.
#7
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#9
Ok, went out and turned the key and listened for the fuel pump- got nothing. By-passed the ballast resistor and got nothing. I have no fuel pump at all now. It won't even kick on when I actually try to start it. One thing I noticed while messing with it, though. The little silver block on the end of the relays on the passenger fender SMOKES a little when I try to start it. Takes a couple seconds, but it puffs out a little smoke. What IS that thing? It has a bunch of wires on it, and one of the cables from the battery bolts to it.
#10
DUH! Starter relay... Been a long day...
Now, the schematics I can find show the fuel pump tied in with the starter relay. Think it's the culprit? If I had wire and a switch at home, I'd wire the fuel pump directly to the battery...
Now, the schematics I can find show the fuel pump tied in with the starter relay. Think it's the culprit? If I had wire and a switch at home, I'd wire the fuel pump directly to the battery...
Last edited by damageincracing; 04-29-2012 at 06:57 PM.
#11
Ok, found a picture of the starter relay, and have a question. The BATT, SOL, G, and - terminals are self explanatory. What is the "F" terminal? I'm led to believe that's the one that goes to the fuel pump. If that's the case, the smoke is coming out from directly above that terminal (the BATT and F terminals are mounted up on mine. Turn the picture 90 degrees clockwise).
#12
F is for the fuel pump. It supplies +12V from the battery to the fuel pump side of the ballast resistor while cranking. It's purpose is to temporarily bypass the resistor (and the low-oil-pressure cutout if you have one) and power the fuel pump directly to start the engine.
If that relay is bad, it could possibly short out power to the fuel pump entirely, although I'd think that'd pop the fuel pump fuse. Since yours is smoking it's probably shot in any case.
If that relay is bad, it could possibly short out power to the fuel pump entirely, although I'd think that'd pop the fuel pump fuse. Since yours is smoking it's probably shot in any case.
Last edited by Radi; 04-30-2012 at 01:38 AM.
#13
Ok, went and got a new starter relay, along with all the goodies to wire the fuel pump directly to the battery. Put the relay in, and whammo... Nothing... Ok, fine, be that way. Out comes the 30 foot of 12 or 14 gauge wire (don't remember which). This suckers getting 12 volts run straight to the pump. Got the ground wire in the connector, plug in the 12 volts straight from the battery, and WHAMMO!... Nothing again... Stupid pump crapped out... So, just because I was irritated and had nothing better to do, I stuck my meter leads into the business side of the unplugged connector to see what I get. Kick the key forward and I get 12.48 volts for a second, then it drops to zero. If memory serves, that is supposed to happen. Good. At least SOMETHING went right. Kick the key forward to start. and voltage jumps back up to over 10.5, which sounds about right, since the starter is a crankin', and I know voltage is going to drop a little when the starter is a crankin'. So, at least now I know I'm getting juice down TO the pump, it's just the pump ain't doin nothin. New pump this weekend. I need sleep... And a little less stress...