THRILLSEEKER

This past spring I switched out my 750 Edelbrocks for 750 Holley DPs. The boat ran great with minimal jetting adjustment right out of the box. About the 4th or 5th weekend out I got into some agressive throttling in rough water, when I came down off plane to an idle the port engine stalled and would not restart. After about 45 minutes of trying to restart, it finally started but was blubbering and seemed to be loaded with fuel. A buddy of mine who is way more experienced with Holley carbs than I am fiddled with it for a while, checked the needle and seat then adjusted the float level. After that it seemed to start and idle fine until the last weekend I ran the boat it did the same thing, started fine, idled fine, ran fine until we arrived at our destination and as soon as I backed out of the throttle the port engine was dead again. 20 minutes later it started and idled fine. Next day it started, idled, ran fine until coming off plane at the ramp and again, port motor dead!

Any suggestions as what is causing this? Havent had any problems from the other motor whatsoever, is this a carb issue, or do I need to look elsewhere?

Underdog88

For what it's worth Tony, swap carbs to narrow down your problem. Cheap and easy to try

mike tkach

iTrader: (3)

you might have some crap in the needel&seat valve,it does not take much to cause a problem,i recomend changing the fuel filter and the needel&seats on that engine.

FIXX

iTrader: (2)

coil, coil wire or distributor pick up..cant fire the fuel if it has no spark..the blub blub blub if from flooding with fuel..coils only act up when their hot..

keith2500hd

shift detent might kill ignition. agree with swap carbs tp see if trouble moves. what are float levels on carbs at fwd/back, i suspect high float level and no vent baffle on that aft bowl. when you come off plane, the fuel sloshes fwd into venturi's.

sprink58

Ask yourself.."what is different between port engine and starboard engine?" I wonder why it does it with one and not the other.

Also...are they marine carbs or automotive. Marine carbs have "J" tube bowl vents that are a bit longer and have less of a tendency to slosh out.

I agree with replacing needle valves and seats front and rear in that carb. It/they might not be seating for some reason. The DP Holley's with the side hung floats can take a lot of shaking around but once that needle valve hanger is bent or out of alignment for any reason...change it...easy to do. when I run Holly's I carry a plastic Zip-Lock bag with bowl gaskets and needle valve seats just for that reason. With the $hit gas we have now days you never know when the ethanol is going to phuk something up.

I love a DP Holley...no flat spots and throttle response is "right now". Pull that carb off and re do the needle valves and seats. I think that will solve your problem.

THRILLSEEKER

Thanks guys, I'm going to swap carbs first and see what happens.

Theese carbs might have 10hrs. of run time since they were new out of the box, and they ran great with no problems for the first 4 or 5 weekends. It didn't start acting up until I pounded the chit out of the boat in some solid 4's. The fuel filters were replaced this spring (roughly 10 hrs.) ago. The coils/distributor pickups, and all other ignition components were new 22hrs ago. The carbs are in fact marine series with J tubes and the neutral safety switches are bypassed. I pulled the needle/seats out of the front and back and there does'nt appear to be anything wrong with them.

I'm getting ready to order some spare needle/seat assemblys and there seems to be lots of options for needle material and seat size. Any suggestions on deciding which ones to order?

sprink58

Ok...now we have a mystery and I'm stumped. Let us know how this progresses because I am about to put a pair of those same carbs on my Vortec 355 roller motors. I have run them before without issue but probably didn't beat on it as hard as you have. I suggest calling Holley and get their thoughts.

Full Force

iTrader: (5)

Tony, double check for vacuum leaks and give it more fuel at idle also see what happens, mine like 2 full turns out on the mixture screws or it will do same thing, also make sure timing is not dropping too much at idle, if you have msd distibutors or spring type advance the springs can make timing change at idle...

THRILLSEEKER

Tim, it starts, idles, and runs just fine after its sat for a while. It only stalls imidiately after coming off plane after a long run. Which leads me to belive its a flooding issue.