GPU fuel problem

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josephpolk99
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GPU fuel problem

Post by josephpolk99 »

I have an 0470 Continental GPU. I put a 2 barrel holley carb on it with an electric carter fuel pump, 7psi 35gph. Sometimes I can't get it to turn over due to lack of fuel and sometimes it will run out of fuel in the carb after I have put the throttle down for a bit. I've been playing with the carb, going rich on it, and that doesn't seem to help much. If I put a 14psi 110gph pump on it, would that be too much? Anybody ever had a similar situation?
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Slidin Gator
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Re: GPU fuel problem

Post by Slidin Gator »

Over pressure pump is a bad move. You have a fuel supply issue. Here is a recent thread with good info on a similar issue.

https://southernairboat.com/phpBB3/vie ... 47&t=73238
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
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Deano
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Re: GPU fuel problem

Post by Deano »

josephpolk99 wrote:
Wed Jul 14, 2021 5:44 pm
If I put a 14psi 110gph pump on it, would that be too much?
YES, absolutely ! That would be to much; doing so would only create other problems.
That Holley carb is designed to run on 7 psi, any more and you're troubles will be a different flavor.

It sounds like you have a restriction somewhere or the pump is tired (how old is the pump?).
Is that 7 psi what it says on the label, or what you are seeing on a gauge?
If the later, where is mounted? ie. where along the way is that pressure reading being taken?
If that is a gauge reading, how much does it drop when you go WOT for a few seconds?

There is a filter right at the carb where the fuel line connects to the bowl, have you checked/cleaned that?
Other possible causes could include:
plugged tank vent could cause suction
filter in tank pickup may be obstructed
tank pickup could be sucking air

If it is grey fuel line like was typically used on outboard motors,
it has a lining that separates and collapses over time and plugs the line.

Any more you can tell us will only help. If you really have 7 psi and the carb's internal
filter is clean, your problem is most likely with the fuel supply and not with the carb.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
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kwanjangnihm
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Re: GPU fuel problem

Post by kwanjangnihm »

Uni Breather Filter Push-In - 3/8in. UP-122

I just added this to my new fuel tank to prevent vent & mud dobber issues.

Image
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.
josephpolk99
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Re: GPU fuel problem

Post by josephpolk99 »

Thanks for the prompt responses. I don't have a fuel pressure gauge, am going to pick one up and follow your directions. I will post a status update later. Again, thanks
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Slidin Gator
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Re: GPU fuel problem

Post by Slidin Gator »

Joseph,

Given your specific complaint, the carb inlet filter(s) would be my first go to. I have seen it many times and keep spare filters on hand for my rigs that run them. I suggest ordering/buying a couple now, if you don't need them now, you will shortly.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
Bamasoflorunner
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Re: GPU fuel problem

Post by Bamasoflorunner »

I have similar set up. There’s more info needed on your 2 barrel set up. Is it new or used? Was it set up specifically by someone for the GPU? Does it have the filter (mine doesn’t)? Are the squirters working if it’s used? Power valve number? Jets number? Accelerator pump size? Most important has the float be set up and checked? John Fenner is a great wealth of info hopefully he chimes in but you need to list a little bit about what the carb is.
Polbear
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Re: GPU fuel problem

Post by Polbear »

^ this. When I got mine it would diesel on shutdown but got crazy good fuel mileage. It was wildly lean.
The sintered bronze filter on the inlet was plugged up.
One squirter was completely blocked and the other partially. Both jets were partially blocked. They installed a 350 on a 500 flange AND the intake tube o rings were toast.

Not to mention the carb was significantly under jetted.

They're not complicated just need to run through everything step by step.
I ended up replacing, fuel pump, fuel line, ultrasonic cleaned the carb and rebuilt, jetted and tuned, new correct power valve, adjusted idle jet and set float. Machined an adapter plate to seal up the intake and replaced intake o rings.

Boat runs incredibly well now, just takes time and patience. The knowledge is here on this forum with the search bar.
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