Sac Solutions

I have a 502 I punched 10 over making 600+ on the dyno. We made many pulls to 5500 rpm with more to go but I would not let the shop owner keep going since I was not going to be running more then 5250 max. OK so on the dyno we used his fuel system (electric pump). I came home and put the stock bravo raw water pump on the motor with the mech fuel pump. No mater what prop I put on I could not get over 4700-4800. Well I always change the impeller every year and found gas in the pulley oil this year. So time for a new fuel pump.

Sorry to be long winded so here is the point. Now I was thinking of what if I was not getting enough fuel on the top end keeping me from getting the R's? What pump would you guys suggest I run. I have found other stock pumps for not much money 55 bucks but at 40 GPH are they pumping enough fuel for me? Should I go electric? I am open to ideas and am not looking to brake the bank since I might have to sell the boat soon. Until then I would like to use it and once I start using it I wont want to sell it.

I should add I have a worked 950QF carb opened up a bit.

Looking for advice and or if you think going larger on the fuel GPH will help me brake the wall I seam to have hit at 4800. Thanks in advance.

Motor started life as a 1994 502 mag gen V. This is the pump I have found from looking on this site others have used for stock motors. Airtex 60932

mike tkach

iTrader: (3)

some gas in the oil cavity is not uncommon.the lube should be changed when you do the engine oil change.i did a 600 hp 518 cu in engine and used the stock 502 pump with great results.

Sac Solutions

I was told if gas was in that oil then the fuel pump was bad. I had no issues when it was running. Just could not hit the R's I wanted in the water. I was hoping I found the lucky fix. LOL

So is there a way to know if the fuel pump is bad? It has 500 hours on it and is 22 years old. I will say it was a lot of gas in the oil. Mostly gas. But then again I have never changed it. I will admit I had no clue it had oil in it. Some boater I am.

So do you think my fuel pump is bad?

endeavor1

iTrader: (3)

May be cheap insurance to change it, however as Mike T said, those stock fuel pumps will support your need. I know several that are over 600 on the factory pump. If it's not bypassing fuel like the diaphragm is punctured, I doubt that the pump is the issue.

Cole2534

iTrader: (1)

Add a fuel pressure gauge if you're nervous, they're a sound investment.

Full Force

iTrader: (5)

I ran the stock pump at 600 hp and 5500 rpm all day no issues.... you have another issue somewhere or a bad pump... be careful you can burn it up easy....

Sac Solutions

Thanks guys I will get a new pump cant hurt. I think it just needs more carb but who knows.

MichiMike

500 hours 22 year old it has to go.These pumps support 525sc also (600sc I believe) that use as much if not more than what a 600hp NA motor would.

dereknkathy

one possibility is the dyno exhaust was far superior to the manifolds you have on the engine in the boat. does 502 mag use 454 mag exhaust or gils? gils should be fine. 454 mag exhaust runs outta gas around 400 hp.

Budman II

iTrader: (1)

What about the rest of his fuel system? I have a lengthy thread on here devoted to the supply lines and tank pickup to support my NA 489 that is making similar power. I had similar symptoms as his with Lightning headers, and the fuel pressure gauge confirmed that I was not getting a steady supply of fuel to the carb. I was advised that the stock 3/8" lines are not adequate for power levels approaching 600+ HP, although some OSO'ers had run stock lines with no issues. Sac Solutions, does your tank pickup still have the stock anti-siphon fitting on it? These can malfunction and be a source of restriction.

But Derek makes a good point - if he is trying to run a motor like this with stock Merc exhaust, he is going to have plenty of trouble getting it to make power on the top end, not to mention the possibility of reversion.