2000 500 HP EFI with starting problems
 

Working on a friends boat that is having a starting problem, wondering if anyone has some ideas.
It's an EFI 500 with a whipple SC.
Has a cold starting problem. Once it starts is will run fine all day, just has the issue after sitting all week or longer.
Does the same thing with 2 different fuel pumps. Motor has spark but plugs are dry. Computer was sent out and reprogrammed also, problem did not change.
Takes about a minute and a half before it starts after sitting.
Any help would be greatly appreciated

Thanks

if im not mistaken there is a cold start injector on the older models. if not there are a couple other sensors to check. i.a.t(idle air temp) and coolant temp. if they are out of resistance they will offset starting and idling conditions. the system starts in closed loop until it warms then usese the varying parameters to fine tune and adjust to run properly as it runs and warms.



good luck.

Sounds like a good place to start, thanks

I have the same problem with my 2001 Whippled 500 efi's, what did you do to fix it?

Thanks

The most important sensors to check are the ECT (engine coolant temp), MAP (manifold air pressure) and TPS (throttle position sensor). False values from any of them during start up will upset the ecm.
The IAT (intake air temp) sensor is hardly used at all for fuel correction but if broken/disconnected it will of course trigger a fault code.

if it responds well when warm but not cold i would look at the cold start circuit[coolant temp sensor ] have you had a chance to run codes on it?

I have the Rinda scan tool and pulled no codes, what I did find though is my base setting for the tps sensor is out of range, merc specifies .45-.55 and both of mine were in the .86-.88 range which was apparently too high for the ecu to be in closed loop idle mode. Twisted them until they read .50 and the motors start fine now! Now my tps is out of range on the top side, my throttle position is at 88% instead of 100% where it used to be.......any suggestions? :angry-smiley-038:

Maybe Dustin can chime in here. I am also having the same problem on my 01 500efi's, both motors do it but one worse then the other. Tps readings are on. It took like 2 min. of cranking this weekend to get them fired up.

Just sent Dustin an email asking for help with a link to this thread, he should know where to start looking. Strip Poker 388 has the same problem with his Whippled 500 EFI's.

My setup....somebody over at BF suggested to cycle the key 4-5 times before cranking to make sure the rail is fully pressurized. I will try that this weekend.