Mercruiser 5.0 EFI starting issues

[kbetts]

I have 2000 Mercruiser with the 305 EFI with about 100 hours on the boat. The boat will start cold fine,idle and pull fine while on the water. When the motor is warm, after sitting an hour or so, it doesn't want to start. When I try to start it, it will idle high and low like it is surging. It will do that a few times and then it will die. I did eventualy get it started both times, but was scared I was going to run my battery down trying. This doesn't happen every time starting warm. I have had the boat out 3 times this year. Day one full tank of gas no startind issues. Day two, same tank of gas, first starting issue. Day 3, the gas was topped off after the 2nd day, but had starting issues again. All of the days I took the boat out was within a weeks time. Took the boat to the dealer and they plugged it into a laptop and couldn't find any bad codes. The dealer then ran the boat in their tank, still couldn't find anything. Sound like a fuel pump or fuel filter issue? Since I don't want to be towed in to the dock any help would be appreciated.

 

[Haut Medoc]

Re: Mercruiser 5.0 EFI starting issues

Wecome to iboats It does sound like a fuel issue....Changing the filters esp. the water separater is a good start for sure...<br />I'm sure you will get more input from those who are more familiar to your specific set-up, so stick around........JK

 

[vipzach]

Re: Mercruiser 5.0 EFI starting issues

Welcome to iboats! Besides changing filters like JK suggested, I would check all you electrical connections, make sure they are clean and tight. Did you happen to check and see if the boat had any spark? What made you think fuel pump or filter, or is that just a wild guess?

 

[tommays]

Re: Mercruiser 5.0 EFI starting issues

Besides the basic need for good cap,rotar,plugs and filters there are issuses with engine box temps that can affect any engine <br /><br />Its in a service bulletin i forget the number BUT a lot of builders dont provide enough air flow in the box to keep it below a temp that can cause starting problems from vapor lock<br /><br />You can run the blower to bring in more air or even open the hatch to see if the motor behaves better if its cool enough<br /><br />tommays

 

[kbetts]

Re: Mercruiser 5.0 EFI starting issues

Vipzach,<br />Thanks for the welcome all.<br />The boat starts and runs when cool, just have this problem when the boat is warm, but not every time. The days I had it out on the water, outside temp. was only around 75 to 80 degrees. The motor temp. was reading around 170 degrees. When I keep cranking over the engine I can smell some gas fumes, and that scares me being on the water. The fuel filter and pump was just a wild guess because the starting issues occasionaly happens. This boat is a 2000 Crownline 205BR. I believe I will start with the water/fuel filter and check the electrical connections then replace the rotor cap.<br />Sound like a good place to start, or should I be looking elsewhere? Thanks for the help guys,<br />Dkidd

 

[TilliamWe]

Re: Mercruiser 5.0 EFI starting issues

Well, EFI is just GMs TBI, and if you take off the flame arrestor, the injectors are right there above the throttle plates. So, it's not uncommon to smell some fuel.<br />Where in Illinois are located?

 

[rodbolt]

Re: Mercruiser 5.0 EFI starting issues

have your dealer test the IAC when the motor is hot, it can pass electricaly and show no codes and stick mechanically. the puter thanks it be a werkin but the pintle, she aint a movin.<br /> usually if stuck open you can hear the air whistle, if its stuck shut it floods and runs very rich at speeds much below 2000 RPM.

 

[kbetts]

Re: Mercruiser 5.0 EFI starting issues

I am from the Edwardsville area TilliamWe. I believe the dealer did check the codes when it was warm rodbolt. What mechanical item should I be looking at on the IAC if it is sticking. When the motor coughs when it dies, it does make a whistle noise. This dealer has a tank, and ran the boat until warm, and couldn't duplicate the issue I had. This is a very respectable dealer, so I believe they looked under every rock they could, short of taking the boat out on the water and running it themselfs. I consider myself as a shadetree mechanic, but not up on all of this electrical stuff. I took the boat out this past Saturday evening and had no issues. I am wondering if I possibly have some bad fuel.

 

[rodbolt]

Re: Mercruiser 5.0 EFI starting issues

the IAC is a stepper motor. the ECU sends commands and looks for a feedback to test the circuits. the pintle is a mecanical shft with a tapered end, as it extends and retracts it alters the amount of air at idle/low speeds. occasionally they stick mecanically. the computer does not monitor actual position on it and only monitors circuit continuity. so its very possible to have a bad IAC and no codes.<br />you can remove the IAC and using the laptop or scan tool actuate it while observing it move. usually if its stuck open it idles fast sometimes as fast as 1800 or so. if it sticks closed it runs very rich until the throttle plates open enough to let the engine breathe.<br />a failing coolant temp sensor or bad connection will usually cause rough running when warm.<br />however that you can see with a scan tool.

 

[daleatskiworldorlando]

Re: Mercruiser 5.0 EFI starting issues

Hi Dkidd and the group,<br /><br />I have 2000 Mercruiser with the 305 EFI with about 100 hours on the boat. The boat will start cold fine,idle and pull fine while on the water. When the motor is warm, after sitting an hour or so, it doesn't want to start. When I try to start it, it will idle high and low like it is surging. It will do that a few times and then it will die.<br /><br />It might be worth while to check to see if this engine uses the water cooled cool fuel cooler. I have found that the slightest wear on the impeller housing (on inboards and bravos) can let hot water drain back in the cooler and boil the fuel (vapor lock) Maybe put your hand on the cooler hose after running and shuting down to see if it gets hot.<br /><br />Maybe a bad impeller on a alpha would do this too?<br /><br />Hope this helps, Dale

 

[Tail_Gunner]

Re: Mercruiser 5.0 EFI starting issues

Nice i have a older (93) 3.0 alpha, it hasnt been serviced in a long time and i am experienceing the very same issue. This vapor lock thing is very common amoung older carbed car's and i think you have found my issue, yet as to the above issue..........doesn't EfI run pressurized pump's @ least 100 psi? If not im betting your desription is spot on.

 

[kbetts]

Re: Mercruiser 5.0 EFI starting issues

Thanks for all of the input guys. I now have a few options instead of going at it blind.<br />Dkidd

 

[kbetts]

Re: Mercruiser 5.0 EFI starting issues

The boat has been in the shop since the day after Memorial Day weekend. I had to be towed in because the boat wouldn't start after sitting about 4 hours on the water. <br />I took the boat back into the shop, and the boat started right up for them. They did get the boat to break for them this time. They put it in their tank and ran it until it came up to temp. They then let the engine heat soak and then the engine wouldn't start. The shop installed a new eletronic fuel pump, water/fuel filter and a new impeller in the lower unit. After all of this, the motor still vapor locks. Shop tells me that I might have a bad tank of gas, to much alcohol in the fuel and that I have a vapor lock situation. They did make me up a primer bulb to install in front of the fuel filter to prime the system to get me going again if this happens to me again. Shop did tell me NOT to leave this bulb in place and it was for a emergency fix, to get the boat started again. After spending a lot of $ and time in the shop I am not really satisfied with a primer bulb and a length of hose to get me going again if it wont start again. Since the boat has been in the shop, I did recieve my manual from Iboats, and did a little reading on the IAC, I at least know where and what it is now.<br />Rodbolt commented on the IAC could be bad. After spending $600 and it still isn't fixed, what's another $80 on a new IAC? Can I test the IAC myself? What do you guys think? Where should I look next? Could it be a fuel problem? dkidd

 

[Don S]

Re: Mercruiser 5.0 EFI starting issues

You might want to have a look at this Merc service bulletin on vapor lock.<br /> http://www.boatfix.com/merc/Bullet/99/99_07.pdf

 

[BIGALF]

Re: Mercruiser 5.0 EFI starting issues

check the fuel screen inside the fuel tank pick up tube. It cost me over $1,000 to find a stupid screen in the pick up tube that got clogged when the boat ran and slushed up the junk in the fuel tank and clogged the screen. It only did this when it was running in the water and not fixed with ear muffs on.

 

[ex747cap]

Re: Mercruiser 5.0 EFI starting issues

How does the cool fuel work. I have efi ,vapor pump, ???

 

[Don S]

Re: Mercruiser 5.0 EFI starting issues

If you have a question, you need to start a thread of your own.

http://forums.iboats.com/announcement.php?f=445