SteveFastech382

I have a 1999 382 Fastech with 502 mags. Seems lately each time we go out the engines at one time or another don't want to start.

I'm beginning to think its heat related ?? It's been in the mid 90's and sunny here. This past weekend we had ran out in the gulf for a bit and then to an island to swim and listen to the radio. I'm always paranoid of the batteries going dead so I start the engines after about a 1/2 hour of sitting. What happens is the engines crank as normal, seem to start to fire and then die. I try again and again. Usually it seem when crack the throttles and randomly it lights and once it revs and starts is good. The second engine still wouldn't start so I let it set with the first engine running for about 5 minutes and the finally right side started.

What would be common to both engines ?? The right side seems to do it more the left. Never does it on the hose. Only seems to be doing when heat soaked. Thanks for any insight guys. SJ

F-2 Speedy

iTrader: (6)

If their mag MPI, cool fuel engines, its defiantly heat related, when you say right engine what one are you referring to, do you open the hatch a bit when stopped,

Br1dgemann

Yes, I would concur that it is heat related.

502 MAG MPI's are susceptible to heat soak / vapor lock - the first gen with the VST, in particular. Especially of your a using ethanol fuel from the local gas pump.

Mercruiser put out a technical service bulletin on the issue.

t500hps

heat soak.....lift the hatch for a few minutes when you first shut it down to let alot of heat out. open it again 5 min before starting if possible and I bet it never happens again.

ALL_IN!

iTrader: (1)

Vapor lock.

Many of us have/had same problem on 502 MPI's. I went the Merc route and installed their add-on pump. It worked really well, and I never had the issue again (you can install this yourself easily). Others have run return lines back to tank, installed better pumps, etc. Many ways to skin a cat.

SteveFastech382

I usually do not open sun deck. I guess in boat talk I mean Starboard side. Lol. Thanks.

SteveFastech382

Yes, I normally run just station pump fuel that usually has the up to 10% ethanol in it. I normally just put low grade in it as well. Would higher octane be less likely to give trouble ??

What is VST ?? Not sure what your talking about there. SJ

SteveFastech382

What are the add on pumps you mention ??

Is the main issue just a heat vapor lock type issue or do the fuel pumps get week over time ?? I'm the type if the two fuel pumps were just showing their age I would replace if I knew it would solve the issues.

Thanks to you all for your input. It's very much appreciated. SJ

Drew555

I can't understand why people put in low octane fuel..... How about we look at this in a different perspective.......let's say you want to bang this hot girl but you have to get her drunk.... What do you buy her? Wine coolers or Jaegermeister shots. Wich one will get you there faster before she starts crying and you realize she is too drunk? And say stuff like I don't normally do stuff like this? My question is .., if she doesn't normally do stuff like this then why the hell is she so good at it? But what I'm trying to say is the more efficient the fuel energy the more the " bang" for your buck. So buy paying less at the pump your getting less energy per gallon therefore less fun for buck. Your ony seeing the cheaper fillup but not how fast it's gone....or.... If you did 100 shots of beer or 100 shots of Bacardi 151 ...get it

F-2 Speedy

iTrader: (6)

be careful what you ask for, if you have the cool fuel system the fuel pump is clear down under the port motor mount next to the oil pan, I changed mine in my 33 OL but its a PITA.............. VST system has the fuel pump mounted on the sea pump housing, I think