Cutting Out At ~14 PSI Boost - Suspect Fuel Pump

[Boost231]

Jumper will be near the alternator. It's not the green one that's a tach lead. It should have a black cover on it. Think the wire I'd grey

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[dynoman]

I believe it's a grey wire .

 

[Terbro]

Anyone have any issues with Kirbin's? http://www.kirbanperformance.com/pr...ADJUSTABLE+FUEL+PRESSURE+REGULATOR+#6547.html

$115...lowest price I've seen for FPR's doing a quick Google search.

 

[Boost231]

That's the one I said to get. Best unit imop

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[Terbro]

You didn't do a pinch test the correct way. You need to block off the return apply power to the jumper wire and see what it does. Should go over 90 imop

Okay...did it. Found the gray wire, jumped it and it stayed steady at 52. So...I increased pressure at the FPR, and the fuel pressure went up fine, all the way to 88, which was maxing out the FPR. When I maxed out the FPR, I could hear the pump's rpms go down, but that might be just because the FPR was completely closed at that point? If I know what I'm talking about; maybe not...kind got that impression. They were perfectly coincided. As soon as I couldn't adjust the FPR anymore, the pump rpms dropped some.

So what does that tell us? Keeping in mind the pressure drops to less than 10 immediately after the pump turns off...and of course, the real problem, pressure dropping during runs. Collapsed sock? Is it time to drop the tank? Looks for kinks?

Can we assume the FPR and pump are healthy at this point? But let me ask you this? Would a *smaller* pump behave like mine is? This doesn't say anything about flow rate, right...only its capacity to produce pressure.

 

[Boost231]

I'll type more in a few but how is the vac line hooked to the regulator? How is it teed into thr intake? Anything else connected to it?

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[Terbro]

I'll type more in a few but how is the vac line hooked to the regulator? How is it teed into thr intake? Anything else connected to it?

See the attached photo. It's not teed to anything.

I doubt this is important, but another vacuum line (the one directly below the FPR line) is capped off. I looped the line around just so it's in sight and pointed it out on the photo in red. What's that supposed to go to?

I also inspected the quality of the connection and tubing at manifold on top of the dog house (which is aftermarket; aluminum)...looks fine.

 

[turbo89]

See the attached photo. It's not teed to anything.

I doubt this is important, but another vacuum line (the one directly below the FPR line) is capped off. I looped the line around just so it's in sight and pointed it out on the photo in red. What's that supposed to go to?

I also inspected the quality of the connection and tubing at manifold on top of the dog house (which is aftermarket; aluminum)...looks fine.

Capped line goes to charcoal canister

 

[Boost231]

Time to drop the tank imop. Regulator seems to be testing fine

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[larrym]

Not sure if it's been asked how is the charging system? Have you checked for a voltage drop while this problem is occurring?

 

[Terbro]

Not sure if it's been asked how is the charging system? Have you checked for a voltage drop while this problem is occurring?

Right, that was a consideration a couple months back. Monitored volts on the Scanmaster during runs, and they'd drop from ~13.8-14.1 to low 12's by high boost. And my fuel pump is hot wired (which wouldn't be represented on the SM's readings, if I'm not mistaken).

Someone please confirm that in the attached pic, the box in red is the fuel pump hot wire kit. This is located behind the fuel tank.

 

[larrym]

Looks like the hot wire relay.

 

[Terbro]

Time to drop the tank imop. Regulator seems to be testing fine

Very good. Thanks for all the input. And even the refresher on jumping the pump. It's so easy to purge the tank of fuel that way!

I'm fairly booked tomorrow. Might be able to drop the tank on Friday morning. If not, it'll have to wait until next week...have my son from Friday afternoon through the weekend.

 

[bison]

Piece o' cake... As I've mentioned, I've successfully r&r'ed a TR motor single-handedly start to finish back in '02. I installed a 5-speed T-10 tranny, mated to a 327 V8 in a Datsun 240Z, had to add a custom slave cylinder and clutch, etc. to it as well - all by my me own self. So I'm very capable. But obviously proper guidance was essential, and having the tools was obviously required as well.

a T-10 is a 4 speed



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[bison]

Right, that was a consideration a couple months back. Monitored volts on the Scanmaster during runs, and they'd drop from ~13.8-14.1 to low 12's by high boost. And my fuel pump is hot wired (which wouldn't be represented on the SM's readings, if I'm not mistaken).

Someone please confirm that in the attached pic, the box in red is the fuel pump hot wire kit. This is located behind the fuel tank.

I'd check every wire in the car especially the grounds. May not be related to the current problem but a lot of possible connectivity issues. Just looking at that bundle with the zip tie holding the connection together and the ignition wires routed the way they are leaves you wide open for intermittent problems.


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[Terbro]

a T-10 is a 4 speed

Thank you. Correction: T-5. I think I was replacing a T-10...I know it was a 4-speed.

 

[Terbro]

I'd check every wire in the car especially the grounds. May not be related to the current problem but a lot of possible connectivity issues. Just looking at that bundle with the zip tie holding the connection together and the ignition wires routed the way they are leaves you wide open for intermittent problems.

I'd love to argue the point, but can't. About 3 months ago, the GEN II went out. Long story short, turns out, it was the stock ground to the MAF (which also grounds the GEN II, since it interfaces with it in the new wiring). It just went out somewhere. Could never figure out where, though I checked all the connections, so I just added a new ground; fixed the prob.

In this case, as I've mentioned, I have spliced in a 10-gauge wire into the stock ground behind the tank, which hasn't helped. I'm going to give this some thought and drop the tank, so I can be prepared to make some improvements once once it's dropped.

I spotted this a couple days ago from Kirban: http://www.kirbanperformance.com/product/229/FUEL+PUMP+FEEDER+KIT+#6751.html

But that block box looks very similar to what I already have. So I'm a bit confused...they're calling it a 30-amp relay, but is it a "hot wire" kit as well? If we look at my post #71, that's what I already have. Of course I want to keep that...but want to upgrade all the pump's wiring.

 

[Terbro]

Okay, let me ask if this has any potential to determine flow rate, vs. a *proper* bench flow rate test:

Set up a hose at the end of the fuel rail with a 5-gallon gas can, and jump the pump and run it for 30 seconds. The DW pump is rated to flow 340 liters/hour (I've also seen 320), which is 34 liters/minute, which is 8.97 (call it 9) gallons/minute. If I ran the pump for 30 seconds, *in the car, under those conditions*, (@~5,700 elevation), could I expect to get anything close to 4.5 gallons?

The reason I ask, is if I got a "yes" answer to that, and ran the test and got significantly less, then I could assume I either have a faulty DW pump or don't have a DW pump. I'd then just buy one, and have it at the ready for when I drop the tank!

 

[No disintegrations]

Okay, let me ask if this has any potential to determine flow rate, vs. a *proper* bench flow rate test:

Set up a hose at the end of the fuel rail with a 5-gallon gas can, and jump the pump and run it for 30 seconds. The DW pump is rated to flow 340 liters/hour (I've also seen 320), which is 34 liters/minute, which is 8.97 (call it 9) gallons/minute. If I ran the pump for 30 seconds, *in the car, under those conditions*, (@~5,700 elevation), could I expect to get anything close to 4.5 gallons?

The reason I ask, is if I got a "yes" answer to that, and ran the test and got significantly less, then I could assume I either have a faulty DW pump or don't have a DW pump. I'd then just buy one, and have it at the ready for when I drop the tank!

Check all grounds as Bison said. Don't forget the battery negative cable going to the engine block.

drop the tank, the short connector hose on the pump hanger could be loose or pinholed, pushed off, etc. You need to look to find out.

 

[Pronto]

If your dropping the tank you might as well pull the pump and inspect the hoses etc. I had an experience with a Fiero that lost fuel pressure when accelerating. The little hose on the pump had a split in it.