Diagnosis please, fuel system, Mercruiser

[Drowned Rat]

Hi all,

So, went to the lake today and engine cranks, but will not fire. Doesn't even try. I know the fuel is good. Last year I had this happen, so I changed out the fuel water separator and after about 5 minutes of cranking, it started back up. So, I tried that this year, when I took the old filter off, it was full of fuel. I installed the new one and tried cranking for a few minutes, then rechecked the filter, it was bone dry. Does this mean the pump is bad?

This is a 4 cylinder 2003 model.

I took the flame arrestor off to see what was happening in there and I can see no evidence that fuel is making its way to the carb.

Any ideas?

 

[Fishermark]

Re: Diagnosis please, fuel system, Mercruiser

I installed the new one and tried cranking for a few minutes, then rechecked the filter, it was bone dry.

That's not good. I always fill them with gas before screwing a new one on - or at least most of the way full. Saves a lot of cranking. But bone dry isn't right.

Could be your pump or could be the anti-siphon valve is stuck. Maybe even a vacuum leak.

Try pulling the fuel from a portable tank and seeing it that works.

 

[Drowned Rat]

Re: Diagnosis please, fuel system, Mercruiser

Yeah, it wasn't running on the filter that was slap full either. Anti siphon valve stuck closed? Where is the valve?

 

[Drowned Rat]

Re: Diagnosis please, fuel system, Mercruiser

So can someone help me determine which pump I need to order? Looking on iboats it lists serial numbers, but the S/N is faded off my flame arrestor. I have a 2003 3.0L 4 cylinder. Which pump do I need to order?

Thanks a bunch,

 

[fishrdan]

Re: Diagnosis please, fuel system, Mercruiser

Your engine should have another serial number tag, metal one riveted to the block, on the bell housing skirt above the starter.

I'm thinking it's this fuel pump Though, I'm not sure I'd replace a $100+ fuel pump without troubleshooting the problem first. Check the stickies at the top of the forum, there is a fuel system troubleshooting guide.

The anti-siphon is on the fuel tank, it's the weird looking hose barb fitting (has a spring and check ball in it).

 

[Oshkosh1]

Re: Diagnosis please, fuel system, Mercruiser

Use a squirt bottle to "prime" the carb. A few squirts(about a tablespoons worth) after filling the FW Seperator may do it.

 

[achris]

Re: Diagnosis please, fuel system, Mercruiser

Temporarily put an outboard fuel line primer in the line and pump fuel up to the carbie... If the engine starts and runs (while you're squeezing the bulb)... you have a pump problem...

 

[howie boat]

Re: Diagnosis please, fuel system, Mercruiser

just rebuilt 470 merc 170 inboard seems to only get fuel on number four can any one help

 

[Don S]

Re: Diagnosis please, fuel system, Mercruiser

you need to start your own thread howie boat, this thread belongs to Drowned Rat and his problem.

 

[Drowned Rat]

Re: Diagnosis please, fuel system, Mercruiser

Hi friends,

Changed out the pump today and engine now runs like normal. I was a little surprised that it had gone bad only being 9 years old. Is that a typical lifespan for these things? I've never run the engine out of fuel before storing for the off season, might that be the cause?

Thanks for all the help, back on the water!

 

[Eric 3.7LX Alpha 1]

Re: Diagnosis please, fuel system, Mercruiser

Two words, ethanol and China.

 

[Drowned Rat]

Re: Diagnosis please, fuel system, Mercruiser

Yes, good point. I'm just curious now, so I took the old one apart and I couldn't "see" anything that looked bad in the old one. Diaphragm was not torn or anything. All gaskets looked in proper order. There were two brass check valve looking things inside that I supposed could be bad, but they didn't look bad. The cam arm (I'm guessing that's what it is called) had a pretty deep groove on it from where the cam was rolling on it, but again, not THAT bad. What makes these things stop working?

 

[ktbarrentine]

Re: Diagnosis please, fuel system, Mercruiser

Yes, good point. I'm just curious now, so I took the old one apart and I couldn't "see" anything that looked bad in the old one. Diaphragm was not torn or anything. All gaskets looked in proper order. There were two brass check valve looking things inside that I supposed could be bad, but they didn't look bad. The cam arm (I'm guessing that's what it is called) had a pretty deep groove on it from where the cam was rolling on it, but again, not THAT bad. What makes these things stop working?

With a little ingenuity and the "right" test setup, you can test those little check valves. Not much you can do about them, but may reveal the "smoking gun"

 

[Captain Mikes]

Hi

I have a 2001, SeaRay 210 5.0 EFI, 351 hours. The vessel is in like new condition .

PROBLEM: Fuel is getting to the inlet on the back of the throttle body. but NOT through the fuel injectors and down the throttle body. I Borrowed a Injector pulsed diode light installed it on the fuel injector connectors crank the engine and there was no pulsing light, I have spark at the coil. I changed the coil out as a precautionary and still the injectors do not fire. The problem started after the battery died and the rain water filled up the engine compartment and flooded out the starter, I replaced the starter and cleaned all the wire connectors all the fuses were good, checked the wire harness to the ECM all seems good. could it possibly be the ignition module even though it is putting out spark the spark seems to be yellowish. The engine cranks and sparks but the injectors will not fire. I checked the ground connectors. There was some corrosion from being submersed. I removed the bolt and all the connectors cleaned and sprayed with corrosion block put back together with a new coil and still the injectors do not fire. Even though the module is putting out spark should I replaced that module, or is the problem elsewhere?

A local Mercruiser dealer had them scope (diagnose) the ECM and they found NO codes . It has Yellow-ish spark! Almost acting like the lanyard is "pulled", I flipped it up and down to see if it reset it, still no fuel. I have checked all the fuses both forward and aft. Circuit Breaker is functioning.

Thank you in advance for any ideas!!!
Captain Mikes​

 

[biggjimm]

You'd be a lot better off to start your own thread concerning your problem captain Mike. You'll likely get more responses than having it buried down in someone else's thread. Good luck.

 

[Captain Mikes]

new to sight cant find blog tab???

 

[GA_Boater]

Look at the top of the page and read the whole thing. This is a forum, not a blog site.