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.

After taking off my throttle linkage and adjusting the throttle stop, linkage, tps sensor and throttle lever rest and wide open set screws my tps reads in the .52 range closed and the throttle is showing 100% at wot. I will run it tomorrow and see how it starts and idles.

I've seen them hard to start when cold on that setup. I think it is because the fuel in the intake evaporates. the injectors are before the whipple and too far away to give it a crisp start when having sat for a week or two.

Where did Merc put the injectors on the 600sci and up?

WOT tps has no bearing on running, you just need to check linkage mechanically, does it go WOT? If it does, leave it, will not effect anything. If it doesn't you have to readjust linkage so you can get WOT. Verify that blades are close to centerline when open WOT, verify linkage hits stop at WOT.

Dustin

Merc has them in the port. This raises the SC a good 3-4".

Always cycle key 3-4 times before starting. Always try starting with throttle in closed position. The fuel does evaporate after a few days, therefore the manifold, valves, etc. are all dry. It takes a bit to get the motor filled with fuel, and this is different amount when it starts later in the day. Therefore its touchy in the calibration. Make it perfect at cold start, its rich as all hell when you later startup. Because the motors always run cold, cold start and later start are very close in temp. We aim for the middle of the road for both.

One thing to note is that starting on a launch ramp is much harder than starting on a regular, flat ground. Because the vacuum is very little during cranking, going uphill makes it that much harder.

No matter what though, for your application, we can custom configure it to make it better via the computer. Every engine is different, as is the application, therefore we sometimes have to fine tune this.

Dustin,
Thanks for all the tips! I have everything perfect on one motor and a few more adjustments should get the other one straight. What effect does the tps sensor have on throttle operation and performance? BTW, I did cycle the key a few times and the motors started a lot sooner.

Lee

Whipple chargers
 

I have a '95 Formula sr1 502 mpi. Starts fine, can't get the idle to come lower than 1250 rpm; surges about 200rpm. Hit the throttle it will rev, then drop to 900for 2/3 seconds then go to 1250 again. Even after reaches operating temp.

This is the older style (mounts off the side of motor) My tps sensor usually mounted on the bottom of the secondary, was unpluged, and pluged into an auxilary fuel pump. (supply fuel to injectors on blower) What exactly does the TPS do?? Especially if it is unpluged. Am I missing a TEE to connect the TPS and the fuel pump. Any help would be great.
Thanks for reading

The Throttle Position Sensor tells the ECU the position of the butterfly, in other words, how much throttle you are giving. The sensor is acutaly a variabel resistor, when the throttle is closed the value will be around 0V and around 5V at WOT. Together with RPM the ECU will then determine how much fuel is needed based on the fuel inj. map.

BTW
I would look at the IAC (Idle Air Control) first, if the idle is rough or RPM cycles up and down.

whipple charged,
How does being on an uphill ramp affect vacuum?