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Discussion Starter #1
Howdy folks. I've been having some major driveability issues in my TJ, and I think I figured it out.


'99, 4.0, manual trans. For a week now, I've been unable to rev much over 3k rpm while in gear - just cuts out, like I'm bouncing off the rev limiter - and when going uphill, I've been unable to give more gas to maintain speed, as it would do the same. I've had a hard start issue for months, but it's gotten much worse lately - 10-15 tries are often needed to start when the engine is cold. In neutral, it idles okay most of the time, with a sporadic rough idle that goes away (has done that for years though). But, as of this week, giving it WOT in neutral takes much longer to reach 5k than usual, and occasionally the engine backfires around 2k.



No useful CEL codes. I thought perhaps the cat was plugged, but no change with an extra O2 bung plug removed, so that's not it, and the cat is new within a year anyway.



So, I rented a fuel pressure tester. This forum seems to suggest the fuel pressure should be around 49 psi even with the vehicle off and the key on, and definitely up there while running. With the engine off, I have to quickly cycle the key on and off to get any pressure reading, but doing that, I can get it to about 15 psi. With the engine running, I get a steady 20 psi, except at WOT, where it drops to around 16. I'm thinking my issue is the fuel pump. Would you folks agree?



Now, onto that question. I've read not to bother with any fuel pump except Bosch. Bosch no longer makes the complete assembly. I replaced my fuel pump with a Delphi assembly from Autozone about 4 years ago when the original died, and no longer have the original. Do I need to replace the other stuff too? Will the Bosch 69316 unit available on Amazon fit in the Delphi assembly? What are the best fuel pressure regulator, filter, and strainer to get, if I can't get them all together? Do I need to replace the regulator at all, with my symptoms?



Thanks for your help, guys.
 

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I’d replace the whole assembly since you’ll already have it out. Also make sure you clean out the tank real well since you can. I won’t argue with those about brands, but I bought a cheap amazon assembly and it’s been running 3 years at 49psi.
 

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I forgot to add, I’d do the whole assembly because it could be any of those items, plugged filter, bad regulator, but most likely the pump. Regardless, your fuel pressure is definitely lacking.
 

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Discussion Starter #4
Called Autozone, my current assembly has a lifetime warranty on it. So I can get a new Delphi unit for free. I'm tempted to do the warranty swap, then buy the Bosch pump anyway and put a new Bosch pump in a new Delphi assembly. Warranty won't be good if I just swap pumps anyway, and this way I'd get a new regulator, float, and strainers, etc. for free too. Or I can just use the Delphi pump.
 

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Called Autozone, my current assembly has a lifetime warranty on it. So I can get a new Delphi unit for free. I'm tempted to do the warranty swap, then buy the Bosch pump anyway and put a new Bosch pump in a new Delphi assembly. Warranty won't be good if I just swap pumps anyway, and this way I'd get a new regulator, float, and strainers, etc. for free too. Or I can just use the Delphi pump.
I doubt that the Bosch pump will fit the Delphi assembly. Maybe, but doubtful.
 

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X2 on Delphi and on taking advantage of the Lifetime replacement. I used to run Bosch complete assemblies exclusively on my Jeeps. At least until they became scarce for a period, came back for a while at a considerably higher price, then became scarce again. Now I run Delphi pumps in two Jeeps and haven't had a problem. Like others have said, take advantage of the Lifetime replacement!
 

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Discussion Starter #9
Just got my free Delphi pump, thanks guys. I'm still debating whether or not to get a Bosch pump to swap in - I'd rather pay the $55 now than do this again in another four years, but if it doesn't fit, it'd be a waste of money.



I have another question though. I had a little piece of paper towel stuck in my anti-siphon ball spring (long story), and it had been preventing me from using the gas pump setter thing - I'd have to pump very slowly to get gas to go in at all. While taking that out today, I accidentally pulled out the spring with it. Now, the Jeep never took gas very well pre-paper towel anyway, and I'm not really that worried about having gas siphoned out of my Jeep anyway. Do I need to put the spring back in? Will not having the spring make gas go in easier, or harder? If I don't have the spring, do I need to pull the little ball out? If I've got to put the spring back, any tips on how? I'm sure I could finagle it back in, I'm just tempted to leave it out - but don't want to be dropping the tank again if it makes matters worse. Thanks guys.
 

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Another vote for using the Delphi pump since it is free. Now that you've done the work to replace it once you'll know that it really isn't that difficult to replace if it goes bad. Odds are that the Delphi pump will last long enough to justify its cost, of zero dollars.
 
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