Motor Help Needed!

[hre423]

So I made a post a few weeks ago asking about vapor lock on my Ilmor 625s because one of them was starting up and then shutting off immediately after. Took it in, found bad fuel pump and cracked header. Got everything fixed and had them do spark plugs and change oil. I picked it up this weekend and took it out and it did the exact same thing. Ran great in the beginning of the day until we stopped for about 2 hours to hangout, when I went to leave, I was idling out of the no wake and same motor died. Then it started doing the same thing where it starts up and then shuts off right after. Mechanics are stumped at what the issue could be. Has anyone experienced anything like this? Thinking it might be electrical/computer issue?

 

[monkeyswrench]

Don't know Illmor stuff, but do they have the sensor in the raw water intake like the Merc's? Sounds like a temp sender/warning deal possibly.

 

[DarkHorseRacing]

Still sounds like a vapor lock condition. When you sit for a bit somewhere, do you open your engine hatch a bit to release heat and let in cooler air? That might help if you try that. I'd that works then you know its vapor lock. If it has no effect, it could be something else.

 

[Bpracing1127]

Fuel vent clogged ?

 

[hre423]

Still sounds like a vapor lock condition. When you sit for a bit somewhere, do you open your engine hatch a bit to release heat and let in cooler air? That might help if you try that. I'd that works then you know its vapor lock. If it has no effect, it could be something else.

It did it about 5 minutes after I launched one of the times as well so the motor wasn’t even hot yet. Temps are all normal. I do keep the hatch open when cruising and run the blower often as well

 

[rivermobster]

If you're trying to diagnose this yourself...

You need 3 things for an engine to run. Fuel. Air. Spark.

You need to determine, which one is going away, before you do anything else.

Once you know that, then you can process with the next step in trying to figure out the root issue.

 

[4Waters]

If you're trying to diagnose this yourself...

You need 3 things for an engine to run. Fuel. Air. Spark.

You need to determine, which one is going away, before you do anything else.

Once you know that, then you can process with the next step in trying to figure out the root issue.

^^^This^^^

It's safe to say you have air, the next easiest thing to check is spark. Carry an extra spark plug with you and when it doesn't start unplug the easiest plug wire and plug the spare plug in and see if you have spark.

 

[Javajoe]

Makes ya wonder if you really had a bad fuel pump

 

[Javajoe]

Did you ever call Kevin at EE?

 

[Todd Mohr]

Water in your gas, I heard the Ilmor’s are super sensitive

 

[DarkHorseRacing]

It did it about 5 minutes after I launched one of the times as well so the motor wasn’t even hot yet. Temps are all normal. I do keep the hatch open when cruising and run the blower often as well

Ok I don't believe that was mentioned before. But like others mentioned that does change things. I don't know Ilmor engines so not sure what they use for ignition system but it might be worth doing some electrical checks and potentially changing out the ignition box, checking the coil, or checking the distributor or wherever the engine gets its signal to fire the plugs.

 

[DRYHEAT]

Just throwing this out there, check the connector wires between the boat harness and the engine harness, could be an intermittent short, where the engine wire loses connection in the run position, but it will still sputter and try to start while cranking. I had one do that to me years ago. Jumper wire fixed the issue. Not an Ilmor.

As someone said earlier, you could carry an extra spark plug or just go down and get an Harbor Freight spark tester, and put it between one of the plug wires.

 

[Rennsport]

One thing that comes to mind is fuel cell venting. i don’t know if there is a vent check valve in the fuel cell. Might be worth loosening fuel cap when/if this happens again. Certainly frustrating I’m sure.

 

[Eliminator21vdrive]

If you're trying to diagnose this yourself...

You need 3 things for an engine to run. Fuel. Air. Spark.

You need to determine, which one is going away, before you do anything else.

Once you know that, then you can process with the next step in trying to figure out the root issue.

 

[jailbird141]

If you're trying to diagnose this yourself...

You need 3 things for an engine to run. Fuel. Air. Spark.

You need to determine, which one is going away, before you do anything else.

Once you know that, then you can process with the next step in trying to figure out the root issue.

Funny the things someone remembers, you sound just like my auto shop teacher in high school. No matter the problem, he would always start with the simplest checks and go from there.

 

[n2otoofast4u]

Water in your gas, I heard the Ilmor’s are super sensitive

This!

 

[dnewps]

So I made a post a few weeks ago asking about vapor lock on my Ilmor 625s because one of them was starting up and then shutting off immediately after. Took it in, found bad fuel pump and cracked header. Got everything fixed and had them do spark plugs and change oil. I picked it up this weekend and took it out and it did the exact same thing. Ran great in the beginning of the day until we stopped for about 2 hours to hangout, when I went to leave, I was idling out of the no wake and same motor died. Then it started doing the same thing where it starts up and then shuts off right after. Mechanics are stumped at what the issue could be. Has anyone experienced anything like this? Thinking it might be electrical/computer issue?

Do you have a see through hatch? Do you have fuel returns to the tank?

 

[Mototrig]

Sounds more like ignition/electrical.

How hard is it to swap ignition boxes from one motor to the other? Or the coil? Might be worth doing if not a PITA. If if the problem follows the component, Bob's your uncle.

 

[relaxalot]

On the merc 600s it helps to cycle the key to turn on the fuel pump several times before actually engaging the starter. If you just crank it when hot sometimes nothing.. but cycling the key two or three times applies more fuel pressure to the rails. When I changed fuel hose diameter problem went away.

 

[DaveH]

If you're trying to diagnose this yourself...

You need 3 things for an engine to run. Fuel. Air. Spark.

You need to determine, which one is going away, before you do anything else.

Once you know that, then you can process with the next step in trying to figure out the root issue.

actually, nowadays, you need FOUR.

fuel spark and air.........yes........But an EFI engine........lots of electrical connections, sensors and wiring all working in unison are a must. having seen the Ilmor harnesses, i would not be surprised if there is an intermittent electrical connection causing this.

 

[rivermobster]

actually, nowadays, you need FOUR.

fuel spark and air.........yes........But an EFI engine........lots of electrical connections, sensors and wiring all working in unison are a must. having seen the Ilmor harnesses, i would not be surprised if there is an intermittent electrical connection causing this.

Well...

If you don't know what your missing, how do you know what connections to look at?

Always start with the basics.

Throwing darts isn't the best way to diagnose.

 

[ChrisV]

See if you can hook up a laptop and see the data. But I would check fuel pressure when it happens. Sounds like you replaced all those stuff for nothing.

 

[n2otoofast4u]

Dane at D1 just helped my buddy out with the same issue on the same motors.

 

[Deckin Around]

Funny the things someone remembers, you sound just like my auto shop teacher in high school.

My auto shop teacher just said “it’s gotta Suck, Bang & Blow.” That definitely stuck in my head.

 

[DarkHorseRacing]

My auto shop teacher just said “it’s gotta Suck, Bang & Blow.” That definitely stuck in my head.

You missed “Squeeze” between Suck and Blow. Sure sounds like a good porno movie!

 

[hre423]

See if you can hook up a laptop and see the data. But I would check fuel pressure when it happens. Sounds like you replaced all those stuff for nothing.

Fuel pressure was all over the place prior to fuel pump replacement, but this weekend it was steady. Hoping it wasn’t for nothing lol

 

[hre423]

Dane at D1 just helped my buddy out with the same issue on the same motors.

Do you know what it ended up being? I’ll have to give them a call!

 

[n2otoofast4u]

Do you know what it ended up being? I’ll have to give them a call!

Water in fuel. His symptoms were identical to yours!

 

[hre423]

Water in fuel. His symptoms were identical to yours!

Was it only happening to one motor? I didn’t think it would be something with fuel quality/water since only starboard was doing it? Thanks!

 

[Todd Mohr]

A guy I know had similar symptoms and draining the tanks cured it, used the old fuel in his truck with no issues. We all thought it was vapor lock.

 

[Todd Mohr]

Was it only happening to one motor? I didn’t think it would be something with fuel quality/water since only starboard was doing it? Thanks!

Same as my guy, only the starboard motor was doing it.

 

[hre423]

Same as my guy, only the starboard motor was doing it.

Interesting, second person to say that. That was one of my original thoughts but shop didn’t think so. Thanks for the info! Will try that and cross my fingers that does the trick

 

[t-bag]

Interesting, second person to say that. That was one of my original thoughts but shop didn’t think so. Thanks for the info! Will try that and cross my fingers that does the trick

Out of curiosity do you fuel your boat on the water? Please reply the outcome of your problem. Thank you

 

[DarkHorseRacing]

Don't Ilmors run fuel/water separators? Highly recommended in marine environments.

 

[colenighthawk]

Don't Ilmors run fuel/water separators? Highly recommended in marine environments.

Yes they do, they also have a high pressure fuel filter

 

[monkeyswrench]

Yes they do, they also have a high pressure fuel filter View attachment 1439427

Could "D", the regulator/filter be failing and bypassing too much at random intervals? That, or possibly pulling air at the separator?

 

[colenighthawk]

Could "D", the regulator/filter be failing and bypassing too much at random intervals? That, or possibly pulling air at the separator?

It sounds like he has 2 - 625 ilmores, if there is an issue with the quality of the gas, both engines would do the same thing. But only one is acting up.
He already changed the fuel pump. There might be an issue with the fuel filter/ regulator. I have the same engine in my Magic, never had an issue, even tho I don't do much to it, other than - fuel/water separator, impeller, oil change and filter. This engines are pretty much bullet proof.

 

[Jay Dub]

On the merc 600s it helps to cycle the key to turn on the fuel pump several times before actually engaging the starter. If you just crank it when hot sometimes nothing.. but cycling the key two or three times applies more fuel pressure to the rails. When I changed fuel hose diameter problem went away.

X2 for this. I was taught to do this on my fuel-injected setups.

 

[hre423]

Out of curiosity do you fuel your boat on the water? Please reply the outcome of your problem. Thank you

No I don't. I actually haven't even got to fill it up myself yet. Bought it about a month ago and haven't even gotten to drive it more than an hour without having an issue. It had full tanks when I got it.

 

[coolchange]

If you're trying to diagnose this yourself...

You need 3 things for an engine to run. Fuel. Air. Spark.

You need to determine, which one is going away, before you do anything else.

Once you know that, then you can process with the next step in trying to figure out the root issue.

3?

 

[Riverhound 2.0]

Prestige Marine and Pro Marine have fuel test equipment; I believe they can test octane levels. If the boat has been sitting for a while, it could be an ethanol/water content issue. There may be other shops in town that can test fuel, but these are the only ones I know of.

Chris @ Prestige helped me work through a bad fuel issue. It might be worth a fuel test before you start replacing more parts.

 

[DaveH]

Well...

If you don't know what your missing, how do you know what connections to look at?

Always start with the basics.

Throwing darts isn't the best way to diagnose.

Well...

If you don't know what your missing, how do you know what connections to look at?

Always start with the basics.

Throwing darts isn't the best way to diagnose.

you start by eliminating sesnors/connections that would stall the engine. This would be crank/cam sensors or a MAP sensor. could also be a bad fuel pump relay or associated connections. could also be a faulty idle valve. i would start by swapping all of these sensors from one engine to the other and see if the issue goes to the ther engine.

Prestige Marine and Pro Marine have fuel test equipment; I believe they can test octane levels. If the boat has been sitting for a while, it could be an ethanol/water content issue. There may be other shops in town that can test fuel, but these are the only ones I know of.

Chris @ Prestige helped me work through a bad fuel issue. It might be worth a fuel test before you start replacing more parts.

if it was a fuel issue, then seems reasonable both engines would have similar symptoms.

 

[rivermobster]

you start by eliminating sesnors/connections that would stall the engine. This would be crank/cam sensors or a MAP sensor. could also be a bad fuel pump relay or associated connections. could also be a faulty idle valve. i would start by swapping all of these sensors from one engine to the other and see if the issue goes to the ther engine.

if it was a fuel issue, then seems reasonable both engines would have similar symptoms.

Well that's definitely one way to start.

And who knows, you could get lucky!

Or not.

To each his own.

 

[Riverhound 2.0]

you start by eliminating sesnors/connections that would stall the engine. This would be crank/cam sensors or a MAP sensor. could also be a bad fuel pump relay or associated connections. could also be a faulty idle valve. i would start by swapping all of these sensors from one engine to the other and see if the issue goes to the ther engine.

if it was a fuel issue, then seems reasonable both engines would have similar symptoms.

If I remember correctly, the F29 feeds each engine from its dedicated fuel tank (the port tank feeds the port engine, and the starboard tank feeds the starboard engine), so it is possible he could have bad fuel on one side and not the other, only affecting one engine.

When I had similar issues with my boat, I was sure it was a sensor, injector, electrical connection, or something similar. It turned out to be bad fuel in one tank.

This shit has gotten too complicated for me; that's why I pay people who know what they're doing to fix my junk.

 

[DiamondDave]

Everybody keeps saying it can't be fuel related since both engines are not doing it, but nobody knows how his fuel system is plumbed. Maybe I missed that part, and I don't know what boat he has so this may not apply at all.

My N-tech has separated tanks and the complete fuel systems are isolated from each other.

Reason I bring this up is because when I bought mine from the biggest dealer in the country in LOTO, one engine would not run for them. They thought it was fouling plugs and had supposedly "fixed" it before I took delivery. They proceeded to replace a bunch of shit (fuel pump included) to the tune of 6k that did not fix the issue, and the bastard ran for 20 minutes after I bought it. They totally missed the fact that it had bad fuel in it which was loaded with water and tons of trash...

It took me a long time to flush that tank out since they are baffled and as I trailered it would stir everything up and when it sat it would settle again. I was changing filters everytime I ran it, draining fuel from them into a jar for inspection and cutting the filters open to inspect.

If the Ilmors are as sensitive to fuel as stated above, don't rule out the fuel/ tanks especially if it sat alot you don't know what's in them.

 

[ChevelleSB406]

@SJP , didn't you have vapor lock issues on an ILMOR boat, the TOAD painted one? My memory is going these days but its ringing a bell.

 

[t-bag]

I think one of the first things I would do is drain the affected engines fuel tank, replace filter and water fuel separator. Take fuel samples in a clear glass container, fill with fresh gas and retest. Not to labor involved and on the relatively cheap side.

 

[n2otoofast4u]

Vapor Lock, Anyone Else?

So I just got my F29 with twin fresh ilmor 625s. It ran great first ride until we stopped and hung out for about an hour, then one of the motors would start right up and die after about a second. Mechanic is thinking vapor lock and that I just need to crack the hatch more and run the blower more...

www.riverdavesplace.com

 

[Bigbore500r]

Id start with making sure fuel is good and all filters are clean. Don't forget the tank pickup that feeds that motor!

Here's some easy tests to determine if fuel or spark related
(Skipping fuel pressure as you have already confirmed fuel pressure is good - just make sure your checking fuel pressure when problem is occuring is STILL good)

When the motor is acting up and failing to start - give it a spray of brake cleaner or starting fluid into the throttle body.
If it fires and runs - it's not a spark issue, its fuel related. If not - it's spark / ignition related.

If brake cleaner of starter fluid made it fire . . . now you need to see if it's a fuel supply issue, or if injectors are not being commanded to fire.

Easy test #2 (motor is still not starting or wont run) - hook a test light to one of the fuel injector connectors, and see if the light flashes when the motor is cranked over. If not - your injectors aren't firing, and no fuel is being dispensed into the motor. Either the ecm is not firing the injectors due to a safegaurd or sensor value being missing or out of range, you have a failure of the ecm driving the injector circuit, or you have an intermittent issue with a fuse / power or ground that is causing that to happen.
If the light does flash, but still not starting (assuming fuel pressure is showing ok) - This leads back to either lack of ignitioin / spark, or depending on placemnet of your fuel pressure gauge, possibly vapor lock or air in line. The efi filter shown in the schematic posted is a GM style regulator / filter with a return, so it is unlikely this would trap air upstream of that filter. If the pressure gauge is upstream of that filter (it should be, as spec is regulated 58psi) then you are almost certain the injectors have pressure. Again - points to lack of spark or ignition.

 

[rivermobster]

I KNOW you know better than this!!!

A fuel injector has voltage at all times.

The computer Normally supplies the Ground circuit to the injector. It you hook a test light to Anything computer related, you'll likely fry the computer.

The correct way to verify the ECU is trying to fire the injector, is to use what's called a Noid Light. You plug it into the injector connector, and see if it flashes, or not.

OTC (3054E) Noid Lite/IAC Test Kit https://a.co/d/bsEivzX