PLEASE help 502 mag mpi efi dying out after run
 

New to forums.. Please some info. I on boat now and getting annoyed!
1996 SR1 271 502 mag efi/mpi. New boat for me
I pretty good On cars and most motors and issues but.... Here my prob
Bought boat used know nothing about history.
Starts right up runs great at all rpm's run all day fine... After sitting no matter if twenty mm or two hours fires right back up revs fine take off 25 yards starves out and quits????????
Will refire instantly but can't throttle up. After 8-10 restarts it will
Be fine?????? Changed all filters fluids and cleaned the VST filter?
Seems like a mechanical pump feeds VST mid back of engine? Seems to be fuel related but cannot be 100% sure till
More test... It's just really annoying and making me mad. After it
Re starts it's totally fine runs like new.... And this repeats all
Day long WTF UGHHHHHHHH

try opening the engine hatch when you stop and run the blower it sounds like its vapor locking.

Check the vent for the fuel tank

Almost sounds like a loose ground wire or a battery cable that's loose

i cleaned every ground and battery terminal when i first got it..i am not ruling anything out but hate the guessing game.
thanks so much for fast replies guys..... i tried open enginge hatch everytime... no help..its so so weird ran so good all day i can go full speed or idle around for hours..once i shut off for either 20 min or 2 hr same thing fires right up then can idle or take off fast go about 20yrds and starves out..then back to the 10-12 key starts till it back........ gut feeling with my car knowledge is saying fuel issue.. i dont fully understand the system can someone break it down to me

line goes in by sea pump but its not a mechanical pump like my 454 just looks like round diaphram,,,,then up to vst tank with a float and chamber leacing to pump chamber with filter on bottom...... so the part by the sea pump feeds the vst.... so is that pressure regulated or no? ..

far as the fuel lock i tried taking gas cap off when it was happening and it made no difference..also no problems when filling the tank but not sure if fill vent is related to tank vent when under load?? man i am boggled.. just want to find exactly what it is and fix so i not guessing and doing this when i go out..

gonna try homeade code reader monday afternoon.. also anyone know if codes are stored even when batt switch is off or do i need to reproduce the problem again before pulling codes??? THANKS FOR ANY IMPUT IN ADVANCE!!!

why two fuel pumps...... seems foolish design read about alot of guys getting rid of this set up?

http://www.boats.net/parts/search/Me...LOW/parts.html

http://www.boats.net/parts/search/Me...ANK/parts.html

Fixx
 

My insurance mans boat,,had a similar problem..he would start out with a full tank of fuel,,run out 5 miles and go fishing,came back into the harbour and his boat would die out..(fuel issue) So i removed the the fuel pick up in the tank and inspected it, it was a aluminum pick up tube,so when i tryed to check and see if the tube was threaded into the *90 fitting the pipe broke off in my hand where the threads are..called a tank mfr and they sent me a updated nylon fuel pick up..he said that the aluminum ones always seem to crack at the joint..

boat ran fine on a full tank of fuel and once the fuel went down to 3/4 and you were on plane it was ok cuz the fuel in the tank covered the crack in the pipe..

interesting...but i cannot make this happen its only after driving wether i run up and down lake full bore for hour or little while.... what i dont understand is it runs totally fine wot or idling...its just a resart issue? also not sure how choke works on efi... hoping something stupid like intake air sensor or coolant sensor or something... motor was supposedly redone 90 hrs ago so who knows and i know nothing about guy or shop who did it..have some recipts but they dont tell much...got to love a new boat..my last 252br was totally fine....now new headacke...lol seems like a cycle i buy boat fix everything i can for two years or 3 then sell get new pain in the butt.. lol soon as i get them perfect i sell ans start over..someone tell me why? lol

i will be cheking all suggestions btw thanks again

kinda wonderin if float inside vst is messing up...seems on restart i get as far as that amount of fuel would go then dies..maybe its sticking and not filling vst so when vst empty it quits??? not sure but every cold start 1st start of day never have issue

When you try to restart the boat, do you hear the fuel pump "prime itself" for 2-3the seconds before starting?

If you have an electrical meter, sitting the battery should read 12, running, it should be 14v. . . M m

Does it buZz like a car? Like chevy ? Cause I didn't hear n e thing

Beautiful day but can't risk it again with the family aboard
:(

Do codes stay stored even if battery switch it off

See the attached bulletin.

Jwool thanks so so much all that makes sense for sure..

went out this morning and fired right up
read codes had none
fuel pressure at shrader valve was 35-40
pulled tank vent hose off to blow through seemed fine.
air filter screen is nasty gonna clean that and throttle body.

but makes sense about that bulletin everything makes sense.
gonna put new fuel hose from tank to mechanical on.

being new to 502 efi coming from 454 carb it could just be the way i am operating the boat.. i do sort of let idle some before shut off but prob not enough... and the motor compartment on the 271 is super qhuit i think so that make sense block radiating heat and heating compartment.. i do open hatch before starting but probably not long enough..

so next step for me is fuel hose and try operating it differently..

but sucks i loosing great great day on the water i cant risk stalling again the sides of my harbor channel are all huge rocks.. cant risk it with current yesterday sucked.... had to jump off to save it from drifting into the rock walls...

thanks everyone for input its great help and advise after switching boats to a totally differnt stlye

love the boat though 1996 formula sr1 271 502 mag
hit 60gps(wont lie 59.8) with a 21p at about 5050 rpm and about 64/65 on speedo was my best so far think i gonna try the 14 5/8 x 23p mirage plus see if anymore top end

how do i post pic of it? wont let me

Should be able to click on the paper click and add attachment.

Cleaned air filter and intake
Got fuel hose off apears original so gonna change that to

You could also try and put a 6 gallon tank on it for a test and go out for a rip. This will take out any issue that you may be having with gas, tank.....

that sound like good plan..was gonna try to rig a 5 gallon can to vst inlet gravity feed from there to see... new fuel line today then gonna pull the sender and see if any gell or gunk in the tank..

and gonna dump seperator filter into a glass and let that sit

anyone have opinion on the whole setup 2 fuel pumps? is thier and easier better way?

Does sound like vapor lock. I'm having same issue with one of my 502's (port side).

Make sure you do not use ethanol blended fuel. Even with that the pipeline companies are "blending" so much butane and other crap in our fuels that the VL problem is getting worse. that and the VERY hot weather.

I have been circling and opening engine hatch and running blower for about 5 mins before I go into dock area to drop engine temp from 185 down to 165. Keep hatch open while docking. Not ideal but seems to be helping except on the hottest days then nothing really works.

Vapor locking. Seems more of a problem when hot summer temps are up there as they have been lately and the boat has sat a short time after ran.

A buddy tried the Merc water check valves to keep the hot engine water from flowing back into the fuel pumps and heating the fuel there. Proved to be a waste of money.

Both my motors did it this past weekend. 90*+ temps and humid. 1 time it was 1 motor wouldn't start, next time the other. I simply had to idle around with hatch fully open for seveal minutes till the dead motor would start. Then they would run like no issue. 1 time both motors wouldn't start. Had to put ice bags on the pleniums to get the fuel to flow and start the motors. My pumps are the newer designs that are supposed to aleviate this issue.

Wouldn't a return fuel line solve that?

Have been told that it would.

great great info thanks all... my buddy just said ever wonder why everyone lately has their hatch open its not to show off its to cool it down cause this issue is growing more and more

just reading that gas regular or eythnol blend can boil as low as 140f this sound true? but the ethynol blend (pump gas) 178f and my boat runs 180.....

hopefully since this being new boat to me and dif motor setup its just the way i am driving it.. the merc bulletin does say idle 3-5 min before shut off and keep hatch open much as possible.

i pulled sender and looked in tank with flash light surprised it actually looks really good in there thank god.

put on new main fuel line from tank to mech pump and dissected that..being an original hose from 96 yr of boat it looked great inside when i sliced it open....

also think the napa water separator is wrong i put what was on it when i got it a napa 3225
putting quicksilver on today and draining old into glass to see if any presence of water.

There is no doubt in my mind I would run that return line all the way back to the tank. Maybe a good winter project if you can make it work a little better to get you through the summer. If it is set up properly you will never have to worry about it again. Hatch up, down won't matter it will always start back up.

Jon

Tried the return line trick , Did not work, the VST pump emptied tank faster than inlet line would fill it. To make it start faster hold an old towel under front plenum and bleed vaporized gas by depressing schrader valve while someone else cycles the key.Once liquid fuel is seen it will start. Works for me but be careful.

Where is that Schrader valve. I cannot locate on my engine. Can you snap a pic or give me description of where it is?

Its above the thermostat housing dead center front of engine on bottom of intake mIne has brass cap looks like tire valve stem cap same setup as tire valve you really need to look under intake to see it or teach and feel it hope that helps

have a quick summer fix for ya.. I have a 312 that used to vapor locked all the time... then I pulled the ****ty fuel lines off that run on the motor..dumb design. Moved my water fuel seperator to the back of the back seat off the motor. ran a new s/s braided line from the mech. pump to seperator, then from there back along water pump hose and then over the top/side of MPI plenum then right to VST.. Has helped allot..

follow up:

ok so as i said i am new to this boat and love it... so i read the merc bulliten and have just tried few different things..
been running the blowers as much as possible..also opening the engine hatch much as possible... kinda annoying but the boat has not vaperlocked since i been doing this.. so ill slow down idle in for like 2 min with hatch 1/2 to 3/4 open and its been fine since.. so maybe i just not operating it properly.. but agree with last poster over winter i am gonna revamp fuel system might procharge and just do whole new fuel system anyways... but if not i am gonna move water seperater as suggested and run new lines..

but it has not done it once since i been venting the crap out of it...

My engine very rarely gets over 165 and I am having almost Identical problems and changed or checked everything you have on almost the same boat and am new to the boat as well. Maybe it's a Formula thing, lack of airflow through the hatch at idle? Mine quit me and my young family last weekend and would not start until next day. I was really wanting to find something that made me feel confident it was fixed to try again but I've seen nothing so far.

I had a similar issue, after running would die, sometimes on a cold start. Shifting in and out of F and R would die. Turned out it was a throttle sensor of some sort. $85 dollar part and runs perfect. Private message me if you want more details.

have you tried giving throtle when engine is warm and then start engine ?
if it starts , you probably have problem with IAC valve