BUP

iTrader: (9)

Did not read all the post up here. Here is what I think your problem could be.

1. Coolant temp sensor
2. MAP sensor out of spec range
3. Electric fuel pump - internal check valve problem

I would have thrown IAC in the mix but I seen where you said it was changed. I would scan the motor and look at the ranges of the sensors especially the 3 listed here.

Next fuel injector cleaning & testing. I do not have a the biggest name on the block for doing this type of service, but I have posted some really good info before about what to look for. I have been doing fuel injector flow testing - cleaning services now for over 5 years with a custom professional machine - NOT what you see on youtube - good luck with that.

First thing is any or all basket filters are removed from the injector that is the first step, then the injectors are flow tested to see the results from many test specs like flow rates, flow patterns, leaking, ohms test and so on. Next they are put into a an ultra sonic bath that cleans them up fairly well, some great and some not the best (injectors).

Next the injectors are flow tested again to compare the results from the first time around of flow testing. The flow testing solution is not fuel - mine is a match solution with the same specific gravity of fuel - why because you want it to flow like fuel. Next is, I have a back flush unit that when you turn the injector around, put it in the unit, it will back flush all the bigger particles that could not pass thru the very tiny pintles when cleaning in the ultra sonic bath. Next is after back flushing there is no more flow testing or cleaning solution in the injectors.

Also if the company does not have the back flush unit (many do not especially anyone with ASNU machine) you still turn the injector upside down inwhich dumps most of the flow testing solution fluid out anyways. No one that I know - who does this type of service, ships injectors with cleaning fluid solution in them because your last step is flow testing them, then turn them upside down to drain as much of the solution out. Anyways the very short short story about it. I clean many marine industry businesses fuel injectors from Yamaha to Volvo to Merc to Mercruisers to Johnson / Evenrude for over 5 years now.

HyFive578

iTrader: (3)

Thanks BUP. I will investigate those suggestions. Unfortunately, I winterized yesterday so this is going to have to wait until the spring to get resolved but I will make a note of these now.. thanks!

endeavor1

iTrader: (3)

Had a internal check valve fail on a fuel pump on a 2005 525 that caused us to pull our hair out checking things over. Good luck in you search for the cure.

TWIN-SPINS

cycle your keys,,no cranking,,,3-4 times,,,allow 3 seconds between cycles,,,if your bleeding down to 16psi,,,this will get you back to 38-42psi,,which is what youll need for it to fire-up,,,now you can either live with it,or start going thru your cool-fuel system,ie high pressure fuel pump.

HyFive578

iTrader: (3)

Hmm... that's interesting.. it took over two hours to bleed down to 16 psi.. are you saying that it should hold 40 psi for longer? What is the normal rate of bleed down?

TWIN-SPINS

16 psi is low,,,yes it should hold longer than two hours,,,check one of your other engines for reference,,,if you can still get to it,,you can use a fuel gage to check this problem,while its laid up for winter

HyFive578

iTrader: (3)

I winterized the engines on Friday. I will have to retest in the spring..

HyFive578

iTrader: (3)

thinking about this some more... kinda doesn't make sense because the engine will fire right up when cold and presumably the pressure has been bled down if the boat's been sitting for a week or two...

HyFive578

iTrader: (3)

Now that its spring and I had my first run this past Sunday, I'm reviving this thread from the end of last season as the problem is still there.

Here's the problem:

The motor has a hard time starting when it's been run, sits for an hour or so and then is restarted. When the engine is cold, it fires right up. When the engine's been idling for 10-15 minutes and is restarted, it fires right up. When the engine has been run for 45-60 minutes and then immediately restarted, it fires right up. However, when the engine has been run for that same amount of time, then sits for an hour or two (as in a stop for lunch) and then is restarted, it will crank and crank, but will not start. I can get it to turn over by rocking the throttle and coaxing it somewhat, but it takes a lot of cranking to do that.

Here's what I've already done.

- replaced the IAC
- replaced crank position sensor
- replaced cam sensor
- serviced all 8 fuel injectors and had them flow tested
- replaced fuel regulator
- checked fuel pressure and bleed down after running, (takes about 2 1/2 hours to bleed down from 42 psi to 16 psi)
- checked fuel cooler for blockages
- verified insulation jackets covering all fuel lines going into the fuel cooler

I haven't tried cycling the key 3-4 times before restarting to see if that makes a difference, that's next. Possibly going to take apart the fuel cooler assembly but I'm not sure what I'd even be looking for in there.

Any other ideas people???

F-2 Speedy

iTrader: (6)

I would replace the high pressure pump, I understand the system is holding pressure but that doesn't mean its working correctly all the time, how many hrs are on the pump ? which engine is it


I've got 6 pumps if you want to try one