Mercruiser Fuel Pump Pressure?

alexander38 · Post by **alexander38** » Tue Sep 21, 2010 8:02 pm

Ross I've got old school 454 merc's and the pumps are side mounts and the cam runs them. Replace one last year and the other one this yr. The first one went bad and would pump to much gas and over load the carb. And for you guy with those no2 oil burners I can get a gas pump,plug wires and most likely even a carb that will fit my 454 how long would it take to get a lift pump or a high pressure oil pump but we all have likes and dislikes of our engines. And they all loss us off from time to time.

rossjo · Post by **rossjo** » Tue Sep 21, 2010 9:31 pm

Thank for the tip guys. I've got a lot to check Thursday ... in Hilton Head for a couple day on biz.

prowlersfish · Post by **prowlersfish** » Tue Sep 21, 2010 10:39 pm

Lift pump / oil pump / injector most cases same or next day ups

. Unless your me as I have a stock of these parts and more . It did take me some time to get a injection pump but only becuse I was trying to save $$$$$ and the engine was never down

alexander38 · Post by **alexander38** » Thu Sep 23, 2010 8:18 pm

Hey what's up with that UPS stuff. Ross what are you going to try next.

rossjo · Post by **rossjo** » Fri Sep 24, 2010 8:10 am

Sorry guys - didn't get to try anything yesterday (or today). Busy with business (nice problem).

Humm -

I plan to get some fuel line and eliminate some things to see if I have an air leak.

I plan to pull the fuel pump presure bypass tue off at the pump and check for a plug.

I plan to check the carb for flatness across the top.

I plan to get a miniature Quadrajet and some long needles, pour chicken blood on it and poke it when it doesn't do what I like.

I plan to put a soda straw (3") on top of the float down the middle vent tube and see if it rises and lowers as the float works. Not sure this will prove much as I cannot duplicate the problem on the hill.

I plan to determine which fuel pump I have and replace it.

I'd like to get a fuel pressure gauge and plumb it in to see what pressure I'm getting. Unfortunately, this will require flooding the boat while on the water and dropping the anchor and either getting it running after 20-30 minutes or getting a tow home.

Lots of plans - no time (today).

Any other ideas that I should try that would be quick and easy?

alexander38 · Post by **alexander38** » Fri Sep 24, 2010 11:48 pm

Just one but it involves a candle and gas leak and a swim.

alexander38 · Post by **alexander38** » Wed Sep 29, 2010 9:51 pm

Any up dates yet.

rossjo · Post by **rossjo** » Thu Sep 30, 2010 8:42 am

Been busy - and then this tropical depression came through and its rained for days ... fishing tomorrow ...

alexander38 · Post by **alexander38** » Thu Sep 30, 2010 11:22 pm

We know about the rain, we've gotten 10" since last Sunday.

rossjo · Post by **rossjo** » Thu Sep 30, 2010 11:40 pm

Sun finally popped out late today - coming your way. Can't work though - need some time on the water - going fishing instead

douglasgawron · Post by **douglasgawron** » Sat Oct 02, 2010 8:22 pm

I have been having same problem with my carb. I have cleaned it 4 times put in a rebuilding kit. Did not like the brass float so put in new original plastic float. still flooded. Fuel pump is new. Today i took top off carb and held needle closed while cranking engine. fuel was held back. then cranked engine while holding down float pin so float could press against needle normally. fuel shot up in air. float is unable to hold back fuel. Next I'll try to test fuel pump pressure to see how close to 4-5 it is. This is a new pump so it may be too exuberant for some unknown reason. if i find solution i will post for your benefit.

rossjo · Post by **rossjo** » Sat Oct 02, 2010 8:31 pm

Douglas - I appreciate the help!

douglasgawron · Post by **douglasgawron** » Fri Oct 08, 2010 4:40 pm

well i seem to have fixed my carb flooding problem on the quadrajet
i ordered and installed the original plastic float instead of the brass float that was in the rebuild kit
i bought a fuel filter that is also a water seperator similar to an auto oil filter. with the base it was about $50. and i eliminated the old gas filter that was an in line auto type.
that did the trick for my 260 hp mercruiser. i hope it helps you solve your problem.

prowlersfish · Post by **prowlersfish** » Fri Oct 08, 2010 6:03 pm

Never seen a brass float on a quadrajet .

rossjo · Post by **rossjo** » Fri Oct 08, 2010 11:16 pm

I've got two of them. One on my Vette and one on my Chaparral. Maybe they don't have them in VA?

The old foam floats soak up fuel over time. Bad news.

Haven't had time to work on mine. Worked on my dock this am - and fished all afternoon (lots of Sheepshead - great dinner).

Trojan Boat Forum

Mercruiser Fuel Pump Pressure?

carb flooding on mercruser quadrajet