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Loosing power under throttle...


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So I'm on my way to California with the MJ, and encountering a new issue. As I drive, after an hour or so, it starts bogging under throttle. Initially I can't go past 3000rpm, and it slowly drops until it starts cutting out at 2000... not ideal when I've got mountains coming up.

I've checked fuel pressure while it's hot, and I've got 31 at idle, 39-41 with the regulator vacuum unplugged, but it drops to ~20 psi at wot with the regulator off.

I've bypassed the ballast resistor.

I have perfect continuity to ground at the fuel pump's connector, although the connector is a little corroded. I've tried cleaning it off, no help. I couldn't find power at either other terminal at the connector with key on, but it runs and idles great.

I've stopped at every parts store I've seen in the last 1000km, and none had the pump in stock.

I'm in Medicine Hat, about to try the Canadian tire. Might pick up some foil to wrap around the fuel rail while I'm there.

Once it cools down, it's fine for a while.

I've got a set of spark plugs to put in in the morning (when I won't burn myself) but I'm out of ideas. Flat Saskatchewan highways are fine as long as I don't need to pass, but I don't think I can get up mountains like this.

I also only have codes 12 and 55.

I even on the right track with fuel?

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Well, managed to find a pump. It's the Delphi, but at this point I'll take it. Also picked up a filter (herp derp, the parts drone reminded me) and a bottle of injector cleaner.

I should add the reason I suspect the fuel pump is because I've never replaced it and have no reason not to believe it isn't original. It's at least four years old. Also I had to kick the bottom of the tank a few times back when I swapped the engine after it sat 16 months, and it's slowly been getting louder.

I'll do the injector cleaner and filter first, and then do the pump once I've drained the tank a bit more.

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do you have a exhaust leak that could cause the cps to get over heated? I see that happen before.

 

I have had a pin hole in the gas tank hose above the pump and after it been pumping a while it would stretch out and the engine would loose power. I let it cool then good for a bit again. Tell it just would not rev anymore.

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I think it's a fuel problem too and the answer will be obvious when you pull the pump Gog. Crud from a rusted tank in the inlet sock (if it's still intact) causing fuel starvation for the weak pump. Hopefully the injector cleaner and new filter will get you by for the trip.

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Well the injector cleaner did basically nothing. I think I'll swap the pump in tomorrow morning, and the spark plugs too. Haven't ever had them out of this engine, would have changed them a long time ago, but my neigbour is all "I want to learn how to do car things" and she's hot but she's allways busy... But that another problem the Internet can't solve for me...

Made it another 150 km down the road and it was good for a little while but quickly lost power, at this point I've got 1700rpm and no more. Just pulled away from a light, think I might have done zero to 30mph in about a minute. No bueno. Something that puzzles me a little though is it backfires like crazy if I push the pedal down too far, almost makes me wonder if it's an ignition thing. I guess we'll find out in the morning.

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Um... Without admitting to anything, let's just say that catalytic converters aren't relevant to this discussion. We'll see in the morning what's going on.

Just changed a taillight bulb and discovered I also need to actually redo the taillight harness that's been hacked to $#!&. It appears that instead of just having sketchy trailer wires, I have the joy of having hacked off sketchy trailer wires. Somehow haven't really looked at them in four years... I just wanted to fix one thing today... :(

Well, at least I unclogged the a/c drain tube, so that's something I guess.

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I've experienced similar symptoms in the past, not exactly the same platform, but...

Replacing the fuel pump and finding a obviously clogged fuel filter sock solved it for me.  Replace the after pump filter also. 

I suspected heat soak/vapor lock at the time, but the pump/filter solved it.

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The pump I pulled out is a LOT bigger than the Delphi FE0108. Gonna take some creativity to get it in there. But otherwise the sending unit looked great. The sock has some gunk on it but not a super huge amount. This tank is much cleaner on the inside.

ZCqJykX.jpg

Picture's blurry cause it was taken through a ziplock because new phone+gassy fingers.

 

The pump that was in there is a Bosch, numbers on it are 9580810019, 069-11, 31, 8933003591 0J11.

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It had a couple, but they weren't quite up to the task. But with some creative hose clamping it worked out. I'm not convinced all the fuel is coming through the sock now, but the tank didn't look bad inside so I hope it's still good. The truck starts better now than it did as well. Also the spark plugs weren't awful, but it's definitely been running pretty lean. Hopefully this is the fix. Feels a bit up on power from before, but time will tell. Getting back on the road now.

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Well, made it all the way from Lethbridge, AB to Ritzville, WA, just short of 500 miles, with no issues. Well, I suppose I was getting concerned about the trans or throttle valve because it wasn't kicking down the way I expected, even rest the tv cable a couple times, but the solution was as simple as putting it back in power instead of comfort. :wall:

Seems the new pump did the trick. It's great to have my truck back. "Accidentally" left some rubber on an on-ramp or two :thumbsup:

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Um... Without admitting to anything, let's just say that catalytic converters aren't relevant to this discussion.

 

 

Heh. They aren't relevant to anything on my truck either.

 

Glad to see you got your issue straightened out.

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Only 113 degrees in Death Valley today.

 

I honestly didn't need to know how hot it was yesterday. Had to shut off the a/c and prop the hood open to make it up the hill and out, couldn't quite bring myself to turn on the heater...

Unfortunately we're on the way back to Monterey, then we'll likely be heading north to get home. as much as I'd love to go out and visit everywhere, we're on a pretty tight schedule.

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