V3 Install Under Way Finally

Chuckman · Oct 25, 2015

I was really hoping the 155 was a typo as i didn't know they really made them that small. DEFINITELY upgrade it. A 255 walbro is cheap insurance, and the install isn't that bad (drop in).

JD1964 · Oct 25, 2015

My son had it out at a car meet last night. He knew to keep it limited to 5k rpm until we figure out the stumble, bla bla bla..... He calls me from the meet and says the car is cranking fine but wont start. I go out there and run through the usual, spark at the coil, spark at the plug, fuel pump running. All that was good so I'm stumped for a moment until I find the harness connection at the MAF sensor had backed out. Shoved it back in and the car starts fine. He later reports to me that the 5100 stumble is no longer there. It's raining now so I can't do further testing today but as soon as I can I'll verify if the loose MAF connector was the problem.

So, is it possible that a loose connection at the MAF could cause higher rpm stumble I've been talking about?

a91what · Oct 25, 2015

I suppose it's possible, I had a loose connection at the salt and pepper connectors one time. Talk about chasing a gremlin!

TOOLOW91 · Oct 25, 2015

If you're doing it just use a 340 and be done its peace of mind.

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1990Coupe · Oct 26, 2015

That pump is way too small, thats a must upgrade IMO. She's not getting enough fuel.

JD1964 · Oct 26, 2015

You all are starting make me realize I might be in for a pump upgrade. No biggie, I can do that. Meanwhile I'm changing to Autolite 24's and gapping at .032.

I was thinking about the stumbling issue. At 50psi rail pressure it was giving me 12:1 AF WOT and getting to 5900 rpm. At 53psi it was giving me 11.5:1 AF WOT and only getting to 5100 rpm. It now make sense to me (I think). The richer mixture demands more from the pump so its hitting the wall at the lower rpm.

Does that make sense?

JD1964 · Oct 26, 2015

John Dirks Jr said:
Meanwhile I'm changing to Autolite 24's and gapping at .032.

Correction, the Autolite 24's are going back because they don't fit. They fit the E7 heads but not my GT40's. 764 is my number and they are among the colder of their group already. They had been gapped at the stock spec of .054. I'm just going to re-gap them to .035 and put em back in.

1990Coupe · Oct 27, 2015

Makes perfect sense. Exactly what happened to me. Stumble on high RPM, the motor was starving for fuel

TOOLOW91 · Oct 27, 2015

1990Coupe said:
Makes perfect sense. Exactly what happened to me. Stumble on high RPM, the motor was starving for fuel

As the demand for volume rises the pump cannot keep up hence the flat spot

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JD1964 · Oct 27, 2015

I'm gonna take a test drive before I change the pump to see if the plug gap adjustment changed the situation. The stumble feels more like an ignition flutter than a nose dive fuel starvation thing.

The 155 lph pump is 40% more volume capacity than a stock 110 lph. Hard to believe my moderate setup would need more than that. Maybe.... We shall see.

TOOLOW91 · Oct 27, 2015

John Dirks Jr said:
I'm gonna take a test drive before I change the pump to see if the plug gap adjustment changed the situation. The stumble feels more like an ignition flutter than a nose dive fuel starvation thing.

The 155 lph pump is 40% more volume capacity than a stock 110 lph. Hard to believe my moderate setup would need more than that. Maybe.... We shall see.

Duty cycle on a forced induction engine brings down the horse power rating on pumps greatly coupled by pump being rated to run at x psi when raising pressure changes the rating as well.

Page 3 and read the part in red

http://fordperformanceracingparts.com/download/tipspdf/properlyselectingeficomp.pdf

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TOOLOW91 · Oct 27, 2015

Calculator says at 6psi of boost with your 50 lbs of fuel pressure you're at with a .65 Bsfc (typical for supercharged application ) for 350 flywheel hp as a guesstimate that you need a 30 lb injector which you have and a calculated pump of 213 lph minimum which puts the reccomeded pump size at 255lph .....

Fuel Injector and Fuel Pump Calculator

Just some food for thought

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JD1964 · Oct 27, 2015

Here's the Walbro GSS340 255lph on amazon for $65. It's pump only.

I just installed the 155lph Walbro not long ago so can use the pick up sock and harness that's already on the car with this higher volume pump?

Amazon product ASIN B002ERGI7QView: http://www.amazon.com/Walbro-GSS340-Fuel-Pump/dp/B002ERGI7Q/ref=sr_1_1?ie=UTF8&qid=1445991021&sr=8-1&keywords=gss+340+walbro

a91what · Oct 27, 2015

Yes. I did this same thing. Bought a 190 then immediately went with a 255

Boosted92LX · Oct 27, 2015

John Dirks Jr said:
Here's the Walbro GSS340 255lph on amazon for $65. It's pump only.

I just installed the 155lph Walbro not long ago so can use the pick up sock and harness that's already on the car with this higher volume pump?

Amazon product ASIN B002ERGI7QView: http://www.amazon.com/Walbro-GSS340-Fuel-Pump/dp/B002ERGI7Q/ref=sr_1_1?ie=UTF8&qid=1445991021&sr=8-1&keywords=gss+340+walbro

Wow. That's cheap. I don't remember what I paid for my 340, but it was waaaay more than that.

FoxMustangLvr · Oct 27, 2015

John Dirks Jr said:
Here's the Walbro GSS340 255lph on amazon for $65. It's pump only.

I just installed the 155lph Walbro not long ago so can use the pick up sock and harness that's already on the car with this higher volume pump?

Amazon product ASIN B002ERGI7QView: http://www.amazon.com/Walbro-GSS340-Fuel-Pump/dp/B002ERGI7Q/ref=sr_1_1?ie=UTF8&qid=1445991021&sr=8-1&keywords=gss+340+walbro

Yes. The gss340 pump uses the stock sock, wiring, and metal housing. I have this pump in my hatch.

FoxMustangLvr · Oct 27, 2015

FoxMustangLvr said:
Yes. The gss340 pump uses the stock sock, wiring, and metal housing. I have this pump in my hatch.

Error I meant I have in my notch

a91what · Oct 27, 2015

I believe the gss 342 is the high pressure model. Works better under pressure. Ha lol punny.

JD1964 · Oct 29, 2015

First test runs after reducing plug gap from .054 to .035 are in.

Still running 155 lph pump.

3rd gear pull WOT straight up to 6000 rpm before letting off the pedal. No stumble, no hesitations.

Boost exceeding 8 psi approaching 6k rpm but took eyes off boost gauge to monitor tach.

Looks like the pressure was blowing the spark out!!

TOOLOW91 · Oct 29, 2015

John Dirks Jr said:
First test runs after reducing plug gap from .054 to .035 are in.

Still running 155 lph pump.

3rd gear pull WOT straight up to 6000 rpm before letting off the pedal. No stumble, no hesitations.

Boost exceeding 8 psi approaching 6k rpm but took eyes off boost gauge to monitor tach.

Looks like the pressure was blowing the spark out!!

I'm glad it's running great . One last thing on the pump and I'll stop breaking balls - I wouldn't want that pump maxed out all the time like that Even if it's working . Takes one lean pull to hurt it bad . If the pump gets to hot etc that's all it takes esp if it's at its peak . I'd consider the 255 or the 340 for piece of mind

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V3 Install Under Way Finally

Chuckman

GTFO you fat, heavy bastard

JD1964

there is enough sticking out to grab on to

a91what

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TOOLOW91

If you're the village idiot what's that make me?

1990Coupe

JD1964

there is enough sticking out to grab on to

JD1964

there is enough sticking out to grab on to

1990Coupe

TOOLOW91

If you're the village idiot what's that make me?

JD1964

there is enough sticking out to grab on to

TOOLOW91

If you're the village idiot what's that make me?

TOOLOW91

If you're the village idiot what's that make me?

JD1964

there is enough sticking out to grab on to

a91what

SendMeUrDataLog

Boosted92LX

It's only an inch or two. What's the big deal?

FoxMustangLvr

I love my Pimp

FoxMustangLvr

I love my Pimp

a91what

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JD1964

there is enough sticking out to grab on to

TOOLOW91

If you're the village idiot what's that make me?

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V3 Install Under Way Finally

GTFO you fat, heavy bastard

there is enough sticking out to grab on to

SendMeUrDataLog

If you're the village idiot what's that make me?

there is enough sticking out to grab on to

there is enough sticking out to grab on to

If you're the village idiot what's that make me?

there is enough sticking out to grab on to

If you're the village idiot what's that make me?

If you're the village idiot what's that make me?

there is enough sticking out to grab on to

SendMeUrDataLog

It's only an inch or two. What's the big deal?

I love my Pimp

I love my Pimp

SendMeUrDataLog

there is enough sticking out to grab on to

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