Weird fuel surge...

[we4Mateo]

I have an odd surge at wot in 4th and sometimes at the top of 3rd. I thought it was the tranny, but the tranny guy doesn't think so. He thinks it's fuel. I am showing not as rock steady afr as normal. I replaced the pump with a new DW pump from Nick and the symptoms persist. FP regulator doesn't smell gassy and pressure holds except small, 1/2lb "blips" at wot. Alky is keeping everything together right now. The plugs looked a tiny bit lean after a hard run today. We tested voltage after the relay and it's good @14.4V with only .3V drop from the battery, but the probe we used indicated fluctuations and was indicating that the voltage was not steady. I'm going to replace the relay in my hotwire anyway, but has anyone heard of a relay that had little drop outs like this?

I have the Casper's relay #108130. It's a 40A relay. My Kirban hotwire kit uses a 30A relay, but he doesn't sell relay replacements. Can this Casper relay work in it's place if needed?

@Dennis Kirban @GNVenom

 

[we4Mateo]

This is probably what I need, but can I use the 40A #108130 that I already have?

Thank you.

http://www.casperselectronics.com/store2/product_info.php?cPath=30&products_id=1036

 

[TurboBuRick]

No reason you can't use a 40 amp. I don't see it being your problem though.

Any data logs?

 

[Pronto]

Have you tested your alky pump with Julio's alky tester?

 

[we4Mateo]

No reason you can't use a 40 amp. I don't see it being your problem though.

Any data logs?

No logs.

Have you tested your alky pump with Julio's alky tester?

And I haven't tested the pump. I can see the "blip" on the fuel pressure when it happens. I thought it was the tranny, but it appears that my fuel fump is intermittently cutting out. I didn't think it was the relay either; they usually work or not right? This hotwire kit is 7 years and 70k miles old.

 

[Jerryl]

. . . . I thought it was the tranny, but it appears that my fuel fump is intermittently cutting out. I didn't think it was the relay either; they usually work or not right? This hotwire kit is 7 years and 70k miles old.

I recall reading a post from Razor about an intermittent relay on a costumers car. Worst case, you'll have a spare.
It is a challenge and sometimes a mystery to achieve true stable FP on these cars.

 

[GNVenom]

Sealed relays that have the same footprint are generally all compatible. Except for the 70 amp Caspers sealed relay, which uses much larger terminals for the contacts.

I once had a fuel pressure surging problem that turned out to be the hose between the sender tube and the pump sucking air. I have since changed my evil ways and located the pump outside of the tank, mounted on the frame, and put the sump pickup at the rear of the tank, where the fuel would slosh to when accelerating.

 

[we4Mateo]

Sealed relays that have the same footprint are generally all compatible. Except for the 70 amp Caspers sealed relay, which uses much larger terminals for the contacts.

I once had a fuel pressure surging problem that turned out to be the hose between the sender tube and the pump sucking air. I have since changed my evil ways and located the pump outside of the tank, mounted on the frame, and put the sump pickup at the rear of the tank, where the fuel would slosh to when accelerating.

Thank you for the info. I've also been thinking it may be time to do a purpose built fuel system and then it's done for the next engine anyway.

 

[we4Mateo]

Could be a fuel filter. Tank was dirty and sock was contaminated when I changed the pump. It would figure that it's simple like that. I'll report back.

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[we4Mateo]

Sealed relays that have the same footprint are generally all compatible. Except for the

70 amp Caspers sealed relay, which uses much larger terminals for the contacts.

I once had a fuel pressure surging problem that turned out to be the hose between the sender tube and the pump sucking air. I have since changed my evil ways and located the pump outside of the tank, mounted on the frame, and put the sump pickup at the rear of the tank, where the fuel would slosh to when accelerating.

How do I tell if the relay has the same footprint? Just the prongs or just the number of prongs?

What I have I believe is this: http://www.casperselectronics.com/store2/product_info.php?products_id=1036

The spare I have is this: http://www.casperselectronics.com/store2/product_info.php?products_id=1102

The hotwire kit I have uses whatever this kit has: http://www.kirbanperformance.com/product/229/FUEL PUMP FEEDER KIT #6751.html

Please advise.

 

[we4Mateo]

Fuel filter, no change. Doing alky filter next and may throw a pump on to check. @Razor , what do you get for one of those pressure testers?

 

[Pronto]

Think it was $80. Found mine leaking. Would never has detected it.

 

[mgmshar]

You probably checked this already, but I had a weird problem like this. I could hear my fuel pump sound intermittently drop down while idling in the driveway. Beat my head trying to figure it out. Turned out to be a loose negative battery cable at the battery. Maybe double check all of the connections for the hot wire, maybe one came loose. A simple loose wire can drive you crazy.

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[we4Mateo]

You probably checked this already, but I had a weird problem like this. I could hear my fuel pump sound intermittently drop down while idling in the driveway. Beat my head trying to figure it out. Turned out to be a loose negative battery cable at the battery. Maybe double check all of the connections for the hot wire, maybe one came loose. A simple loose wire can drive you crazy.

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Good call. I have a bunch of grounds and will check them all as well. I lowered the boost and will check to see for sure which fuel system it is. After checking all wiring, I'll recheck the pump installation. Same symptoms before and after pump install last week. I'll check alky system too and probably clean the nozzle etc just to be sure regardless. Thank you again

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[we4Mateo]

Well I turned off the alky and turned it down to 14psi and it runs smooth as glass. Now I know 20psi is different than 14psi, but I feel like my alky system needs attention next. I'll throw my new pump on, new filter, and disassemble the entire feed line and clean the nozzle etc. If it still has the problem, then I'll race this weekend at 14psi and see what it does. It still feels like it has easy mid-12's in it even at 14psi. Knock free even on the pump swill alone. I'll prob throw a gallon or two of 110 in at the track so it's safe when the TC locks. Glad I can still at least participate in the race.

 

[we4Mateo]

Figured it out thanks to my friend Bob insisting it was ignition related after a ride. New Silverado coil and off to the races tomorrow!

This is my third coil pack since getting the tr6. My first failed one tower and Bob Bailey couldn't figure out why. The second one never worked as well during lean cruise and I should have seen the writing on the wall. It finally started not working as well at wot. I'm sure I could have tightened the gap down from current .040 but then lean cruise suffers. Either way, new $80 delco pack and lean cruise is back, closed loop idle is smooth, and 25psi even with the gap is smooth as glass and like a freight train again. I'll see how long this pack lasts.

One thing is for sure, if lean cruise suffers, I'm changing the coil pack first instead of chasing so many other things. I do now know both fuel systems are checked, filtered, and ready to rock!

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[Pronto]

Why are you seeing such a failure rate for that coil pack?

 

[we4Mateo]

Why are you seeing such a failure rate for that coil pack?

That's a great question!

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[we4Mateo]

My tr6 is hotwired and delco parts aren't what they used to be?

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