Fuel Delivery Issue OMC/5 litre Ford Cobra HO

[Gregor B]

1997 Ford 5 litre HO (raw water cooling) bogs under load after a couple of hours ?
2 Barrel Holley carb - the fuel spray on one side is interrupted as the engine surges and then stalls unless RPM is reduced
I brought the boat to a reputable shop last season for this same issue, they did a tune up replaced spark plugs, distributor wires, cap and cleaned the carb.
The carb appears dirty, carbon ? after only few hours out of the shop. The shop foreman says I should sell the boat & next step is taking a mechanic out on the water?

I like the boat, a 97 Four Winns cuddy and would like to get it running properly & reliably not pass the problem on to someone else.

Your help is diagnosing/repairing this most challenging problem is greatly appreciated!

 

[HT32BSX115]

1997 Ford 5 litre HO (raw water cooling) bogs under load after a couple of hours ?
2 Barrel Holley carb - the fuel spray on one side is interrupted as the engine surges and then stalls unless RPM is reduced
I brought the boat to a reputable shop last season for this same issue, they did a tune up replaced spark plugs, distributor wires, cap and cleaned the carb.
The carb appears dirty, carbon ? after only few hours out of the shop. The shop foreman says I should sell the boat & next step is taking a mechanic out on the water?

I like the boat, a 97 Four Winns cuddy and would like to get it running properly & reliably not pass the problem on to someone else.

Your help is diagnosing/repairing this most challenging problem is greatly appreciated!

Howdy,

Welcome aboard!

It's always helpful if you post your actual model number.

OMC didn't offer a 5.0L engine in 1997 so it's probably a 96. The first 2 models are carb'ed
502APNCA 1996
502APNCS 1996

THese are EFI
50FAPNCA 1996
50FAPNCS 1996

That 2v Holley is a pretty good carb. Depending on how long it sat (old fuel) before you bought it, the problem could be any number of fuel related "things".

Carburetor "cleaning" doesn't tell me much though. I wouldn't say I cleaned a carb unless I disassembled it. If I did that, I wouldn't put it back together unless I replaced all the gaskets. If I replaced the gaskets, it would be a rebuild since you never just replace gaskets.

So, if someone just sprayed "Mechanic-In-A-Can" down the carb, they didn't do ANYTHING. So much for "Reputable Shops" ..............

Holley carbs are very easy to rebuild. ............... so if that wasn't done, that might be my next step after checking the FOLLOWING

Regards,


Rick

 

[Chad Flaugher]

Look at your pulleys... are they pitted with rust? That causes extreme belt wear, and "Belt Dust" which can get into the carb and cause problems. I know because I had that problem with my '74 OMC 5.0 Ford.

 

[vasy]

You can buy a rebuild kit and do it yourself just to make sure.
If that is intimidating, for the price or taking mechanic on the water and trouble shooting old equipment you can just purchase an new carburetor for not less and just swap it out. Also make sure you install some kind of fuel filter as you might have crap in the tank from old age, so good for cheap insurance.