Mercury 2007 90HP 4-Stroke EFI Fuel Problem

I have a 90HP EFI 4-Stroke that while I was trying to start acted like the motor was locked up. I had only tried to start it twice before the problem occured. I had just drove to boat about 30 minutes earlier with no problems. I talked to the dealer on the phone and he said to pull out the spark plugs. I did this after I got the boat home (didnt have the tool with me). When I pulled the plugs out and turned the motor over by hand gas poured out of a couple of the cylinders. Was just wondering if anyone has had this problem before and what the cause was and if any other damage to the motor could have been done when it was hydr. locked. Motor is still under waranty and I havent tried to restart it since removing the spark plugs. Just want to cover myself when I take it to the dealer to make sure any damage that this may have caused is looked at before I accept it back from the dealer.

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

I know what your problem is, a four inch hose( (a 20$ part ) inside the fuel pump failed, and is filling up your crank case oil. and hydro lock is caused by excess fuel in the cylinder. its due to ethanol in the gas which caused the rubber hose to fail. I know I'm finding this might cost me a ton of money to fix mine, so far the cost is over $1,000 and when all is said and done it might cost more, so I'm pissed with only three seasons on the motor

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

not ness a merc problem. Mercury are spec for e 10 gas when the ethanol is added it is added after the storage tank. they dont want it going bad in their tank. test the fuel for % of ethanol . 3 dollar kit save you 100's

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

Only way fuel can get in a cylinder on a EFI is a stuck injector, the crankcase filling will not do it. I would change my user name Blackbird.....

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

Faztbullet said:

. I would change my user name Blackbird.....

Click to expand...

??? Maybe he has a Honda??

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

http://www.ripoffreport.com/boat-de...ries/blackbird-industries-a1-outboa-3c848.htm

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

ETHANOL> get used to it> change all fuel hose>I know this is old but> It happened to me 2 times> We solved it in testing for 2 months> my motor is 2007,115-4stroke EFI>
in the fuel module is a vacuum hose to the fuel regulator. Under "high vacuum" from the intake manifold controlling fuel pressure. fails at lo rpm because that is the highest vacuum. The 1/8" hose "implodes by Vacuum" and "sucks" fuel into the intake manifold> found "fuel locked" 2 times in the bottom cylinder. fuel settle in bottom and is sucked in cylinder.
when it first pops, the engine smokes heavy. If crack is small, it may not lock. Mine did later. solution NOT mercury fix>1/8" ethanol proof high pressure injection hose not the vinyl hose being used(it hardens of 2 years) 2 hoses shown in picture
Another problem found> 3/8" hose to tank> found failing inside. (noted lots of problems on Iboats also) mine was gray hose > used ethanol proof Fuel injection hose from Auto parts.

8/10 /12 Look an current hose mercury is selling for use in the fuel module to the fuel regulator. Talked to exp mech. a the marine shop. At this NC coast marine business they have sold 16 kits. He has seen lots of burst hose. The current hose is the same material but thicker. He has not seen and of those hose burst. Has to heat hose to shape it to fit in the "horse shoe" required. Much thicker hose so wont burst but "may harden over time" it is still some type like Plex hose.
Has not see any of them burst.

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

PontoonboatFun said:

View attachment 162206ETHANOL> get used to it> change all fuel hose>I know this is old but> It happened to me 2 times> We solved it in testing for 2 months> my motor is 2007,115-4stroke EFI>
in the fuel module is a vacuum hose to the fuel regulator. Under "high vacuum" from the intake manifold controlling fuel pressure. fails at lo rpm because that is the highest vacuum. The 1/8" hose "implodes by Vacuum" and "sucks" fuel into the intake manifold> found "fuel locked" 2 times in the bottom cylinder. fuel settle in bottom and is sucked in cylinder.
when it first pops, the engine smokes heavy. If crack is small, it may not lock. Mine did later. solution NOT mercury fix>1/8" ethanol proof high pressure injection hose not the vinyl hose being used(it hardens of 2 years) 2 hoses shown in picture
Another problem found> 3/8" hose to tank> found failing inside. (noted lots of problems on Iboats also) mine was gray hose > used ethanol proof Fuel injection hose from Auto parts.View attachment 162199View attachment 162203View attachment 162204View attachment 162205

8/10 /12 Look an current hose mercury is selling for use in the fuel module to the fuel regulator. Talked to exp mech. a the marine shop. At this NC coast marine business they have sold 16 kits. He has seen lots of burst hose. The current hose is the same material but thicker. He has not seen and of those hose burst. Has to heat hose to shape it to fit in the "horse shoe" required. Much thicker hose so wont burst but "may harden over time" it is still some type like Plex hose.
Has not see any of them burst.

Click to expand...

Just want to say thanks to PontoonboatFun, For posting these pictures. I was able to fix my new boat mercury 75 EFI. I got a great deal on my fishing boat b/c the original owners didn't want to deal with the problem of the engine being hydro locked. Now it runs like a champ.

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

Gents
Be carefull on the hose you choose to fully submerge in fuel. Most dark hoses have a liner which is resistant, but the jacket on the external isn't. I have tested several black hoses fully submerged and they go soft and gui. The inner and outer layer separate. It could be a bad recipe for gummed up injectors down the road....

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

schematic said:

Gents
Be carefull on the hose you choose to fully submerge in fuel. Most dark hoses have a liner which is resistant, but the jacket on the external isn't. I have tested several black hoses fully submerged and they go soft and gui. The inner and outer layer separate. It could be a bad recipe for gummed up injectors down the road....

Click to expand...

What kind of house did u used and how long did it last before it got gui?

Thanks

Re: Mercury 2007 90HP 4-Stroke EFI Fuel Problem

Bigmercury said:

What kind of house did u used and how long did it last before it got gui?

Thanks

Click to expand...

I meant hose!

This was SO helpful! My 2007 90 HP EFI was acting up, I thought for sure the starter was bad because it would not turn the engine flywheel over. Before I ordered a new starter ($350 btw) I read this forum and pulled that module apart last night to find that 1/8" line blown JUST like the above pictures. I pulled the spark plugs and turned engine over and it pumped a large amount of gas out lowest piston. A side note, I also had raw fuel running out the air filter which sent up the first red flags. It has also over filled the engine oil so I had to change it. The one thing I have not figured out is why the battery cable that at the starter would drop to 4 VDC when it was trying to spin hydro locked engine??

I had some yellow 1/8” fuel line that is supposed to be ethanol resistant so we’ll see how long that lasts. I think I might go ahead and purchase a new starter and keep it with me in case because I really don’t want to get stranded again.

I was sitting on the beach for a few hours and when we went to leave I fired the motor up and it ran great for about 20 seconds then all the sudden it started running really rough and died. I got pulled back to the beach and it would not turn engine over. I tried jumping it with another boat but nothing. It seemed like a lose connection but I made sure everything was tight.
Anyway, thank you everyone!

Any chance Dan Mangan you are still watching this thread. I need some help. I have the same issue, my bottom cylinder was fuel locked and fuel runs out the intake manifold when the pump runs. I have pulled the plugs and just the bottom cylinder is filled (now drained). I have new plugs & oil/filter on the way but want to resolve the problem so it does not happen again. I'm going to pull the fuel module cover and look for the possible leaky hose. I'm not sure what else to do form the thread. I assume replacing the fuel line. My gas is on the old side from last season with Merc preservative in it but I'm going to drain it and get rid of it.

Other than that, is this problem solvable by fixing the vac hose in the fuel module? I can't believe this crap from Mercury, what a poor design. I was leary of buying a Mercury but now I'm stuck. Please advise on what to do to fix the issue other than what I've mentioned.

Thanks for the above postings,greatly appreciated.

Old thread and closed. Start a new thread, rebmo.