350mag Hard start when warm

[FISHIN SUCKS]

Anyone know why a 350mag that is warmed up, shut off, and try to restart may have trouble starting or not firing right away yet starts fine when cold? My starboard motor just started this last saturday after making a few hot laps around the lake. Port motor started up just fine (warm). Almost acted like it wasn't getting fuel, would backfire. after trying about 4 or five times to no avail, tried again after leaving the dock about 2-3 minutes later, she fired right up with no hesitations. Temp guages were reading the same on both motors. I noticed someone on OSO is having a similar problem with his '99 28ZX w/350mags. thanx in advance for any help,

tom

[Tidbart]

Question: by chance, did you open the throttle slightly, in neutral, and try to start it?
The reason I ask is that on the MPIs, the throttle plates are fully closed in neutral and the air is supplied through a bypass tube controlled by the IAC motor.

Bob

[FISHIN SUCKS]

Hey Bob, thanx for the response. Never touched the throttle except after trying get her to fire the third time, then it was a couple of raps back and forth thinking I was going to get some fuel up there (kinda like pumping a carberator).

[BUIZILLA]

next time it's hot, before you crank, have someone crank it for you and make sure the fuel pump cycles between key on and crank... should cycle for about 6 seconds, maybe longer, if it doesn't the pump is bad, or if it does it may be weak, if you lose fuel pressure after a hot shutoff it won't start until the pressure builds... or the regulator is weak and leaking down... if it vapor locks you will get air before fuel at the schrader valve bleeder..

[The Hedgehog]

Ah man, that is a big problem. Pretty much the only way to solve that is to pull out both engines and install some 400+ CID SBC's that make around 550hp a side. The only issue with that is your boat may go too fast and you may have to sell it for a Caravelle or a Baja if you can't handle it.

You would also be at risk to win a peoples choice award.

[Tidbart]

Hey Bob, thanx for the response. Never touched the throttle except after trying get her to fire the third time, then it was a couple of raps back and forth thinking I was going to get some fuel up there (kinda like pumping a carberator).

Unfortunately the MPIs don't work like that. I would do the checks that Buizilla suggested. A fuel pressure gauge would help analyze the problem. Attach it to the shrader valve, that Jim alluded to, on end of the fuel rail.

On a good note, you have a twin right next to this one to compare readings, etc. with.

B

[FISHIN SUCKS]

Unfortunately the MPIs don't work like that. B

I know you're right, it's just a habit and I did it. Thanx for all the help guys, I'll do some checkin.

Very funny stuff Hedge! I'm thinkin Caravelle with a scum line

tom

[Ed Donnelly]

I am showing my age here, but, is it possible that the timing is a little too far advanced..

On my Pantera, it would start cold but barely turn over hot and it was a bad ground............Ed

[mrfixxall]

check iac motor, may be sticking due to carbon build up..get some throttle body cleaner and clean them..some didnt have iac motors but theirs a idle bleede tube with a filter on it, filter gets plugged and wont idle or rough time starting..usually the bleed tube is on the big blue motors but you never know with berc changing things around.

[Sweet Cheekz]

You would also be at risk to win a peoples choice award.

As I recall its the light show that draws em in

Parnell

[FISHIN SUCKS]

As I recall its the light show that draws em in

Parnell

Draws'em in.......but never wins