North American Turbocoupe Organization



84 Bucking under boost... fuel pump?
RC Martin Offline
Posting Freak
#1
I recently noticed some hard bucking and hesitation at high boost and rpm at highway speed. I don't remember noticing it before, but I don't drive it on the highway often. I'm running 15psi with a rebuilt motor and big FMIC, car has tire shredding power and really moves until it cuts out. Reading around it seems like the fuel system is the likely culprit since I don't think I have blown a HG. I already have a Kirban AFPR that's dialed in, but stock fuel pumps. I believe my inline pump has been changed before (13+ years ago) but I don't know what's there. Considering the 2.3 crowd all says the dual pump setup is actually superior, I am considering just dropping in an inline 255 HP type pump, the GSL392 from APE http://www.autoperformanceengineering.co..._pump.html

Is this a good idea or any other ideas or suggestions would be welcome.

I've got other worries like a new clutch and exhaust system on the horizon but this is a new priority...
84 TC - Bright Canyon Red, Rebuilt Motor .040 Over & 3-Angle Valve Job
Gnari FMIC / Recirc Pipe / HKS-SQV BPV, Stinger MBC @ 15psi, RF-E6 Manifold, Remote-Mount TFI, PC1 and Flowed 35# Injectors, Inline Walboro 255HP, Kirban AFPR
Rebuilt Suspension -- KYB & Energy Suspension
http://www.cardomain.com/ride/2289955
Reply

Jeff K Offline
Administrator
#2
Dont guess..... get a fuel pressure gauge and see if KOEO pressure is around 39 psi after a few key on/off cycles, or whatever base pressure your Kirban is set to. If that checks out see if pressure under boost is base press + boost press. If so, your fuel system is fine.

Some parts stores may rent fuel pressure gauges with a small deposit.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Reply

RC Martin Offline
Posting Freak
#3
I just bought a FP gauge, seems like a lot more of this kind of stuff is becoming more affordable https://smile.amazon.com/gp/product/B073...UTF8&psc=1

Hopefully I will have time to check it out this week.
84 TC - Bright Canyon Red, Rebuilt Motor .040 Over & 3-Angle Valve Job
Gnari FMIC / Recirc Pipe / HKS-SQV BPV, Stinger MBC @ 15psi, RF-E6 Manifold, Remote-Mount TFI, PC1 and Flowed 35# Injectors, Inline Walboro 255HP, Kirban AFPR
Rebuilt Suspension -- KYB & Energy Suspension
http://www.cardomain.com/ride/2289955
Reply

RC Martin Offline
Posting Freak
#4
So with el cheapo gauge I was getting about 35 psi after a few KOEO fuel pump primes, and about 37-38 psi base FPR engine running. This is down from where I set it about 6 years and 4k miles ago, at 39-40 psi. El cheapo gauge also seems to only take pressure as if it's a check valve, fill up with gas in the line, and then stop working. So I'm hesitant to go for a drive to check pressure under boost. I tried to set the base pressure up around 40 again, and I'm going to get the HP 255 in-line and a new fuel filter on order and may loan a better gauge to set with after the swap.

Also, no pressure bleed-down observed but I am hesitant to trust el cheapo FP gauge.
84 TC - Bright Canyon Red, Rebuilt Motor .040 Over & 3-Angle Valve Job
Gnari FMIC / Recirc Pipe / HKS-SQV BPV, Stinger MBC @ 15psi, RF-E6 Manifold, Remote-Mount TFI, PC1 and Flowed 35# Injectors, Inline Walboro 255HP, Kirban AFPR
Rebuilt Suspension -- KYB & Energy Suspension
http://www.cardomain.com/ride/2289955
Reply

RC Martin Offline
Posting Freak
#5
Verified the in-tank pump is still running also. Swapped in the inline Walboro 255HP and reset the base FPR with engine running. No KOEO codes given besides a healthy 11. It doesn't seem to be fuel related but I am not able to do a driving FPR check yet... this gauge leaks like a sieve at the schrader valve with the fuel pump running.

Went for test drive, the issue is still there if not more pronounced than before. It loses power and shudders about about 10-12psi of boost, otherwise runs fine. This is a new development and it wasn't doing it before, now it's cutting out even in around town with boost.

What else could cause this issue, I wonder? Timing got off somehow? I don't have any blown HG symptoms, either...
84 TC - Bright Canyon Red, Rebuilt Motor .040 Over & 3-Angle Valve Job
Gnari FMIC / Recirc Pipe / HKS-SQV BPV, Stinger MBC @ 15psi, RF-E6 Manifold, Remote-Mount TFI, PC1 and Flowed 35# Injectors, Inline Walboro 255HP, Kirban AFPR
Rebuilt Suspension -- KYB & Energy Suspension
http://www.cardomain.com/ride/2289955
Reply

Jeff K Offline
Administrator
#6
How old are the plugs? What brand, type (copper, platinum, etc) and what is the gap? Might try a new cap and rotor. They can both carbon track and kill spark under load. What brand plug wires? How old?
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Reply

RC Martin Offline
Posting Freak
#7
I just put in new MC sp447 plugs a few weeks ago actually, gapped at 36 if I recall. All the rest of the ignition is motorcraft, very low mileage but over 6 years old now. Cap and wires look okay, have not pulled the cap to check the rotor yet. Timing was advanced maybe two degrees the last time I set it, haven't checked it in years either.

The only other new addition since this issue started was a turbo blanket, but I can't see how it would be related...
84 TC - Bright Canyon Red, Rebuilt Motor .040 Over & 3-Angle Valve Job
Gnari FMIC / Recirc Pipe / HKS-SQV BPV, Stinger MBC @ 15psi, RF-E6 Manifold, Remote-Mount TFI, PC1 and Flowed 35# Injectors, Inline Walboro 255HP, Kirban AFPR
Rebuilt Suspension -- KYB & Energy Suspension
http://www.cardomain.com/ride/2289955
Reply

Jeff K Offline
Administrator
#8
Are the SP447 plugs the direct replacement copper plug for the OEM plugs? Not familiar with the newer Ford plug numbering scheme, as I have been running NGK plugs in all my cars for years.

Could always try closing the gap to .032 and see if that makes a difference.

How old is the coil? Motorcraft or aftermarket? Plug wires routed correctly?
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Reply

RC Martin Offline
Posting Freak
#9
Yep, that's the Motorcraft copper plug for OE replacement.

Coil, tfi, pip, wires are all motorcraft, up to 8 years old but very low miles.

I might try and look for vacuum or boost leaks, too. Reminds me of a boost leak the way the power stops but there is no sound of it...
84 TC - Bright Canyon Red, Rebuilt Motor .040 Over & 3-Angle Valve Job
Gnari FMIC / Recirc Pipe / HKS-SQV BPV, Stinger MBC @ 15psi, RF-E6 Manifold, Remote-Mount TFI, PC1 and Flowed 35# Injectors, Inline Walboro 255HP, Kirban AFPR
Rebuilt Suspension -- KYB & Energy Suspension
http://www.cardomain.com/ride/2289955
Reply

RC Martin Offline
Posting Freak
#10
Gapped at 36, '84 gap spec is 32-36. Have not adjusted to try 32.

Did a full fuel pressure check today and everything is golden, including driving under boost. Got a couple ignition parts on order...
84 TC - Bright Canyon Red, Rebuilt Motor .040 Over & 3-Angle Valve Job
Gnari FMIC / Recirc Pipe / HKS-SQV BPV, Stinger MBC @ 15psi, RF-E6 Manifold, Remote-Mount TFI, PC1 and Flowed 35# Injectors, Inline Walboro 255HP, Kirban AFPR
Rebuilt Suspension -- KYB & Energy Suspension
http://www.cardomain.com/ride/2289955
Reply





Users browsing this thread:
2 Guest(s)



Theme © iAndrew 2018 - Software MyBB