Fuel Problem
 

I was changing the water pump impeller on my 454 mag, which has the fuel pump that is mounted on the sea water pump. When i took the fuel line off the pump that runs to the carb no fuel came out. Should there be fuel in this line all the time or does it bleed off whent the motor is off?

I have been having problems starting the motor after is sits at the beach. Once started it will run fine but after i sit at the beach all day it takes a while to start.

Could the fuel pump need to be replaced. I have seen other posts that you can get a fuel pump from Autozone to replace, but wasnt sure how good those work with boats.
Thanks

It really should not bleed back since their is a one way check valve in there. And that would explain a hard start after sitting for a while. You really cant use an automotive starter because they do not have the port for the overflow line that runs to the intake. The boat would not be CG legal without it. But there are rebuild kits available for most of the pumps, which should have new valves in them.

Is the check valve in the fuel pump? I replaced the anti syphen vavle that is on the fuel tank.

The fuel pump has at least 1 inlet and one outlet valve, sometimes more. they keep the flow going from the tank to the carb-all one direction. If the fuel drains back out of the carb line then one or both valves are likely leaking some.

Thanks. I may just replace the fuel pump then go from there.

The pump from Autozone is a marine pump, made by Airtex, the OEM maker for Mercruiser. Details in my post here:
http://www.offshoreonly.com/forums/d...fuel-pump.html

[QUOTE=apollard;3135401]The pump from Autozone is a marine pump, made by Airtex, the OEM maker for Mercruiser. Details in my post here:
http://www.offshoreonly.com/forums/d...fuel-pump.html[/QUOTE

Wow, great find. Sorry I had not seen your post, that is a great deal. And I have black paint :drink:

I credit Google - they did the searching of other forums

apollard - are the fittings located in the same spot as the mercruiser pump

Yes, the ports are in the same locations. You'll need to remove the brass fittings from the old pump & install on the new one - same as the Merc part.

I was looking at reviews on these pumps and they are not real good. Do you know of a lot of people running these. Just dont want to get a bad one and be stuck on the water.

I'm running one. Have 30+ hours on it and no issues. Don't know anybody else here running them, most of the guys I know are running EFI.

Where did you see reviews on this pump? I didn't see any when I looked.

remove the check valve at the tank and check it,it has a ball&seat and a spring,they can and do cause problems like you have.

I ordered one last night, saved me some coin! I owe you a few beers-shots. Got plenty of paint! Haven't pulled water pump/fuel pump system off yet, I'm hoping the finger on the pump is wore out and not the cam on the shaft. Lost fuel pressure at high rpm, been chasing high rpm miss for a week and a half. Every thing ignition wise is good, only thing left is fuel. Should had it straight a week ago, but time has been my enemy..............................Rjr............ ..................

I just searched for airtex on google and it came up with reviews

Interesting. I searched for airtex, airtex reviews, and airtex fuel pump and got an amazon page for an EFI pump (4 stars rating) and a chevy EFI pump that some people complained about and some said worked fine. Nothing on this pump, but I only went a couple of pages deep on each search.

This Airtex pump is only rated at 40 gallons per hour. Is that enough fuel for a 454 mag? or even a 330 HP 454?

I did a check on Autozone's site for fit, and any BBC vehicle I choose states that it doesn't fit (maybe because it's a marine pump).

The Holley marine mechanical pumps are rated at 110 gph and 130 gph for BBC. That's a big difference between 40 gph and 110 gph.

What is the original fuel pump rated at?

-Bill

Not sure where you got the gph rating for that specific pump, but:

Assuming a brake specific fuel consumption of .5, a 330hp engine needs 165 lbs / hr of fuel. Even using a typical outboard engine (or turbocharged engine) BSFC of .6, you need 198 lbs/hr. 40 GPH is 224 lbs/hr. So the pump would be fine.

Using the old rule of thumb of 1 gph / 10 hp (which is conservative for todays engines), the pump would support 330 hp with ease.

The 400+ hp Ford 427 used a stock pump rated 40 GPH (at pressure). Lots of other '60 muscle car engines turned big HP numbers using stock 40 gph pumps - including lots of 454s.

People try to hugely oversize their pumps (bigger is better!), and the aftermarket encourages that. Saying a stock pump will work doesn't sell new parts. The holley pump is rated 110 gph at free flow. Stock pumps are rated at pressure, not free flow (SAE specs). How much does the Holley flow at 6-7 psi? They don't tell you - because it's not going to be much more than the stock pump.

Why do I say that? The stock fuel pump cam gives a set stroke. To keep the dimensions of the pump reasonable and the pump reliable, the width of the pump (and therefore the diaphram) cannot be much more than stock. The capacity of a diaphram pump is determined by diaphram area(for a circle, that means width) and the stroke. You can change the stroke the pump sees by changing the pivot point of the shaft, but there are limits there also - as the pivot point moves out, the force (and therefore pressure) it can develop drops. The ultimate limits of a mechanical pump is designed into the pump mount & cam - and that limit isn't almost 3x the stock pump flow at pressure.

(Note that I am not saying the Holley is a bad product - it's a darn good one, IMO - just that you don't need it to make hp.)

I'm running the Airtex 60932 on a mild 7.4 (probably 350 hp), and it holds WOT (4800 rpm) as long as I want with no signs of leaning out. In fact, the plugs look a little rich.

The Merc pump I looked at at the dealer was an Airtex pump, with the Airtex markings.

And with that, I'm done trying to save folks a buck.

Apollard,

I got the GPH rating of the pump directly from the Autozone product information page:
Also, thanks for the other information about pumps. I will be in the market for new fuel pumps, so this topic is very current for me. It looks like I will get two of the pumps from Autozone, and paint them Black.

Will this pump work bolted directly to the block (Mark IV), or does it only work bolted to the sea water pump. I have a 454/alpha combo, so I need a pump that will bolt directly to the block.

Again thanks for the info.
-Bill

Now that I can't answer - mine mounts to the sea water pump. Look at the catalogs to compare the part numbers, that might tell. Mine is a 1994 7.4L.

Airtex only lists two pumps for the 7.4 engine:
60932 - 92-93 - GM Mark V eng, w/ 4bbl carb
41416 - 79-90 - Chev eng after 1-31-79, Dual diaphragm pump, inlet 9 O'Clock, outlet 8 O'Clock.

But looking at the picture (both on Airtex's site and Autozone), it doesn't look like the stock pump. It also doesn't look like it has the fuel nipple that runs to the carb in case the diaphragm ruptures. Also the 41416 pump runs 88.99 at Autozone. I found the Holley 712-454-11 Marine 110 GPH Mechanical Fuel Pump on Amazon for $93.25 with free shipping. Not a big difference in price for the AirTex. I wish the other Airtex pump fit my 454/Alpha Mark IV.

Any other ideas?

Thanks for your help,
Bill

Same motor and I replaced the high pressure pump in the vst tank last year and has ran great until the last couple of times out, if I drop it too fast back to idle it dies and will start right back up with a lil bit of throttle. Has anyone else experienced this? Im looking to replace this sea pump mounted fuel pump to see if thats it, but higher rpms are fine.

Well, I found the fuel pump for the my 330 HP 454 that will bolt up to the block. I looked under Mercury Marine, not Mercruiser. I don't know why the difference since my engines are Mercruiser. Here is the information:

Part Number: 60601
Weight: 1.8 lbs
Warranty: 1 YR
Fitting Size: Inlet - 1/4 in. - 18, outlet - 1/4 in. - 18
Fitting Type: Inlet - NPSF, outlet - NPSF
Gallons Per Hour: 50
Pressure Rating: 6 - 7 1/2 psi
Shipping Information: Overnight and Two Day shipping are not available for PO Box, APO/FPO/DPO or US Territory addresses.

BTW - this pump is only 55.99!

-Bill

These fuel pumps worked great! Installing them, and bending the lines were a real B@#$h, though. It took 3.5 hrs to install the pump on the port engine, and 2.5 hours to install on the starboard. That's 6 hours of marine tai chi.

The boat finally runs great. I was having issues with the starboard engine for a few years - not getting full RPM out of it.

Thanks for the help,
-Bill