Ok, so yesterday I was out and had to get a tow back to the ramp because she would not start and idle. I pulled off the fuel filter (cannister) and there was only half left in it, and it was obviously sucking air from somewhere. I have 3/4 tank on one side, and full on the other. So I know it is not out of gas, but it acts the same with both tanks. I do have an IMCO super fuel valve 3 port between the tanks and the inline filter. I have not had a chance to get to the pump yet and see what is going on. Anyone have any ideas? I am gonna try a gravity feed to the cannister filter and see if gets sucked up and starts or not. I was not a happy camper on my first trip out this summer.

electric or mechanical fuel pump?  valve may by stuck and not changing?

Who towed you in? Might want to take advantage of the offer to forum members who join Sea Tow.

This has been one of our most consistent calls we are getting. Every time it seems to be something different, so keep me posted on your findings.

damn jay sorry to hear that on your first trip out.  i think you deserved at least one before an issue!!

It seems there is a major issue with the earlier 500 EFIs and vapor lock. They only have one fuel pump in the system, and it is in a bad spot. The later years had a second mechanical pump in the system to fix the problem. I am working to correct the problem now with possibly another fuel pump and a fuel cooler. I dont like being embarrassed like that being as I am a mechanic and all lol.

And we have a winner! Vapor lock was the issue. I am going to put a second pump in the system and it will solve that issue. So, for anyone with a 502 without the mechanical pump, ensure you idle it down when you park after running, run the blower prior to starting and try to keep the engine bay open for a little while as well to keep the air flowing. I will be installing vents as well to aid in keeping the ole HO moving along :)

Glad Fountains don't have that problem.   ;)

I was just checking and found all the 500 EFI's and at least the early 525's all have the same fuel cooler. You can buy the merc sea pump with the fuel pump drive and the fuel pump for about $500 retail and it appears it uses the same $400 bracket with both sea pumps.

lift pump would be the ticket and much, much cheaper.  $900 bones?  Damn!

Griswald wrote on Jun 26^th, 2012 at 3:13pm:

Glad Fountains don't have that problem.   ;)

Funny you should say that, the first guy that popped up on OSO with that problem when searching was a Fountain ;) It is not brand specific boat wise, only Mercury/Mercruiser wise.

Griswald wrote on Jun 26^th, 2012 at 4:37pm:

lift pump would be the ticket and much, much cheaper.  $900 bones?  Damn!

Both sea pumps use the same bracket. The point was he does not need to buy it.

Yeah I noticed it was the same. Figures I would have that short span of model years with the issues, such is the price of horsepower lol.

Adding a heat shield between the exhaust and the separator filter will help as well. Do you have Gils or Headers?

I have headers. That is a good idea with the heatshield.

Just bustin' balls, Jay.  I've towed quite a few boats with vapor lock issues this year only to have them get to the dock and fire it right up after things have cooled down a bit.  Fortunately, I haven't had that problem.   

I'm looking forward to late September, early October so I can spend spend some time on mine.  I love to stretch her legs in a 20mph north wind.  I've only put about 5hrs on her this year and am a bit itchy.

Jay Gadsby wrote on Jun 26^th, 2012 at 3:00pm:

And we have a winner! Vapor lock was the issue. I am going to put a second pump in the system and it will solve that issue. So, for anyone with a 502 without the mechanical pump, ensure you idle it down when you park after running, run the blower prior to starting and try to keep the engine bay open for a little while as well to keep the air flowing. I will be installing vents as well to aid in keeping the ole HO moving along :)

How do I tell if I have a 502 w/o the mechanical pump? I'm assuming to be in this situation as mine is a 99 Baja 272. Thanks for the tips, I'll follow these next time I'm out as I might be running into vapor lock as well.

Its easy to tell on the 502s. Look at your raw water pump, the newer style has a fuel pump mounted to the raw water pump that is driven by the same pulley. The older style like mine does not have this. For some reason GM designed the Gen VI 502 without the mechanical fuel pump and thus Mercury/Mercruiser had to resort to utilizing the raw water pump shaft for drive. I went the other route and installed a small boost pump inline. I will be testing out that setup today. I am hoping it does not bottle neck me at WOT since supposedly the 500EFIs can drink up to 40ish GPH, and the pump moves around the same. The main fuel pump is still inline as well so I think it will be fine. We shall see today.

By the way, you dont ever run on Belton do you? There was a nice Baja 272 out last weekend, sounded pretty mean.

good luck today jay!!

Thanks Jay I will have to take a look. And no, that was not me on Lake Belton. My 272 is subdued until I put on better exhaust next season.  :)

That stinks, a whole season down :( You gonna run some CMIs? Are you a black motor or a blue motor?

Thanks Nathan! I dont plan on running hard today, I am bringing out my dog for the first time lol.

She ran beautifully, started right up and had no hiccups. I did notice less soot on the ass end, so I am hoping it did not lean her out, but I ndidnt break 60 today, so no WOT.

On a side note, I ran into a gentleman with a 29' Nordic Escape out on the lake today, beautiful boat, one of only 3 made. He said he will check out ABF and may check out Travis next weekend.

Jay Gadsby wrote on Jul 7^th, 2012 at 8:09am:

I went the other route and installed a small boost pump inline. I will be testing out that setup today. I am hoping it does not bottle neck me at WOT since supposedly the 500EFIs can drink up to 40ish GPH, and the pump moves around the same. The main fuel pump is still inline as well so I think it will be fine. We shall see today.

One of the primary reasons the belt drive pump was utilized is safety. The pump can not and does not pump when engine is not running. Another reason is to have the engine installed as a unit  without separate components. Additionally electric pumps push fuel; diaphragm pumps draw fuel.

FYI any fuel electric fuel pump installed in a boat should [ must according to Coast Guard] be installed so that it can not continue to run when engine is not running. The best way to do that is to ground the fuel pump to an oil pressure switch so it can only operate when oil pressure is present.

Another FYI a basic run of thumb for fuel consumption is the engine will consume 10% of its horsepower in gallons per hour. Thus a 500 is capable of consuming 50 gallons per hour.

To be specific the main fuel pump is not inline. It exists in the high pressure loop.