1989 xr4 150 that sat 3 years issues.

[Lt1z350]

So picked up a Norris craft 1750 with an xr4 on it and was told it ran fine last time in the water. This was late in 2019 I was told and been sitting since. The previous owner tried to do the carbs on it so first thing I rebuilt all 3 of them as one the float wasn’t setup right and it was pushing fuel.
The motors oil system has been bypassed so he was mixing it and it had old gas in it also
So got new fuel in it key on with carbs done the electric fuel pump was no longer pushing fuel from the center vent so all seems well on that. I was also doing the water pump and had the lower off it and fired it just let it pop off and idle a second before I put the new pump in it and foot back on it. Idle seemed good for fact no foot on it and just stupid loud.
So now got a set of ears on it and once water pressure came up I could tell it didn’t like that slight load on it though had a decent idle.
I grabbed some new plugs got new fuel and it’s not taking throttle well so something is up with it.
I did a compression test and it’s got 125 on all 6 holes and the initial crank has a strong 75/85 psi first hit. Takes 3 cranks to nail 125 psi so assume the rings are good to go. So next I start pulling off plug wires while it’s idling and wow. So cylinders 1 and 4 are the only 2 that take a big hit when taking plug wire off. All the others when pull it almost don’t notice it. After it runs they have equal heat in them so they are firing somewhat. Checked spark it’s not very strong but it’s there. Plugs come out kinda wet and oily after it runs. The two that are strong are pretty clean while others show carbon and soot.
I know 4 strokes but have not worked on a two stroke since the 80s and my dirt bikes. A buddy said possibly the reed valves got brittle but I don’t know. I bore scoped the cylinders and they look pretty good tons of carbon on the pistons but walls look good no scoring and didn’t expect any as had good compression and equal across the board. So I’m at a loss here on what to do next. Got air got fuel got compression so what is causing the cylinders to be way weaker then the two strong ones? I’m capable just need to know a direction so any help here is appreciated.
The guy I got it from is the son of my neighbor so see no reason to lie to me about it running well last time he had it on the water. His dad gave him a new bass boat so this one just sat in his basement here in Tennessee. So don’t feel like this is a case of bought a boat that didn’t run and was lied to. So assume it’s something from sitting so long
Thanks

 

[Chris1956]

I doubt that motor had an electric fuel pump from the factory.

I doubt it is your reed valves. They are pretty robust.

Look for a mechanical fuel pump and rebuild it, and sack the electric one. A defective fuel pump diagram will flood some cylinders.

Check spark plug wires for arcing to ground. Perform a spark test to assure it has spark to all 6. That motor will have 2 switchboxes, stacked on top of each other, and six coils. Check coil grounds.

CDI electronics should have a ign test procedure for your ADI ignition. Better yet find a factory service manual and perform a link and synch.

carb 2 cycle motors are much simpler than carb 4 cycle motors.

 

[Dukedog]

start it at night without cowl.. screwdriver and check boots and entire length of plug wires...

 

[Lt1z350]

I doubt that motor had an electric fuel pump from the factory.

I doubt it is your reed valves. They are pretty robust.

Look for a mechanical fuel pump and rebuild it, and sack the electric one. A defective fuel pump diagram will flood some cylinders.

Check spark plug wires for arcing to ground. Perform a spark test to assure it has spark to all 6. That motor will have 2 switchboxes, stacked on top of each other, and six coils. Check coil grounds.

CDI electronics should have a ign test procedure for your ADI ignition. Better yet find a factory service manual and perform a link and synch.

carb 2 cycle motors are much simpler than carb 4 cycle motors.

It does have factory wires still and look pretty bad. I pulled one off and it’s still got that yellow/tan sealer at the coil that’s now hard as a rock. At times idling can hear it pick up drop off for sure. As for the pump it’s like a lift pump on the boat next to the tank. Looks old like original and that feeds to the primer bulb then to stock fuel pump. I read last night like you said they can flood the crank case so going to order a kit but will mess with plug wires today.
I had found another old thread if search 150 black max running problems and he had the exact same issues. He threw all the modules a stator all kinds of parts at it. Got better but never right and never mentioned plug wires. Also never says a fix which becomes annoying I hate dead threads so will post what fixes this problem.
I almost feel like when it first fired it was really good then just went to crap over night. Almost like the fuel pump all at once and as it has this lift pump it can still run. I’ll shoot a pic of it in a bit maybe it’s a thing Norris craft did as this style of tank with a pickup from the top and not a bottom gravity feed? If this was a normal car I’d never let it go this far out on stock wires so going to just grab some also.
I have that cheaper manual it came with the boat so will do that test today also make sure it’s all good.
Thanks for advice I’ll get back.

 

[Chris1956]

Outboard spark plug wires have stranded stainless steel conductors. Do not use resistor wire as used in autos.
You can search for aftermarket custom fit from Sierra or others, or use OEM. You can make your own, with new springs, boots etc., however, I would buy them premade, to eliminate any issue with them.

I would like to see that lift pump. I never saw one as described.

All marine fuel tanks pull fuel from top of tank. Bottom tank fuel supply is inherently dangerous as bilge fills with fuel if a leak occurs.

Fuel tanks have anti siphon valve. Maybe yours is clogged?

 

[Dukedog]

yeah.. think those wires are over looked a lot.. any kinda 'lectric pump is an add on.. most carb V6 mercs are still runnin' are on tha mechanical pump... no tellin' why they added a 'lectric one unless they're like me!!!.. or jus lazy 'bout havin' ta pump a bulb up!

 

[Texasmark]

So picked up a Norris craft 1750 with an xr4 on it and was told it ran fine last time in the water. This was late in 2019 I was told and been sitting since. The previous owner tried to do the carbs on it so first thing I rebuilt all 3 of them as one the float wasn’t setup right and it was pushing fuel.
The motors oil system has been bypassed so he was mixing it and it had old gas in it also
So got new fuel in it key on with carbs done the electric fuel pump was no longer pushing fuel from the center vent so all seems well on that. I was also doing the water pump and had the lower off it and fired it just let it pop off and idle a second before I put the new pump in it and foot back on it. Idle seemed good for fact no foot on it and just stupid loud.
So now got a set of ears on it and once water pressure came up I could tell it didn’t like that slight load on it though had a decent idle.
I grabbed some new plugs got new fuel and it’s not taking throttle well so something is up with it.
I did a compression test and it’s got 125 on all 6 holes and the initial crank has a strong 75/85 psi first hit. Takes 3 cranks to nail 125 psi so assume the rings are good to go. So next I start pulling off plug wires while it’s idling and wow. So cylinders 1 and 4 are the only 2 that take a big hit when taking plug wire off. All the others when pull it almost don’t notice it. After it runs they have equal heat in them so they are firing somewhat. Checked spark it’s not very strong but it’s there. Plugs come out kinda wet and oily after it runs. The two that are strong are pretty clean while others show carbon and soot.
I know 4 strokes but have not worked on a two stroke since the 80s and my dirt bikes. A buddy said possibly the reed valves got brittle but I don’t know. I bore scoped the cylinders and they look pretty good tons of carbon on the pistons but walls look good no scoring and didn’t expect any as had good compression and equal across the board. So I’m at a loss here on what to do next. Got air got fuel got compression so what is causing the cylinders to be way weaker then the two strong ones? I’m capable just need to know a direction so any help here is appreciated.
The guy I got it from is the son of my neighbor so see no reason to lie to me about it running well last time he had it on the water. His dad gave him a new bass boat so this one just sat in his basement here in Tennessee. So don’t feel like this is a case of bought a boat that didn’t run and was lied to. So assume it’s something from sitting so long
Thanks

To clarify any possible confusion on Chris' comment: "All marine fuel tanks pull fuel from top of tank. Bottom tank fuel supply is inherently dangerous as bilge fills with fuel if a leak occurs."

"The exit point for the fuel" is at the top of the tank, usually a circular flat plate gasketed to the tank, attached to a tube that picks up fuel near the bottom and usually is screened.

 

[Faztbullet]

Need to do a proper spark check on ignition system...will it jump a minimum 3/8 air gap while cranking?

 

[Lt1z350]

Sorry had a tooth pulled so didn’t mess with it 2 days.
So wires were so bad I mean bad I was excited. Lol I had some Taylor 10.4 from my Tahoe laying around (ls motor). I put some new ends on them and the correct covers from the stock ones and while idle was still not great it took throttle and spun up. Holding at 3k it was almost clean. So tells me keep looking at spark.
So dug in on this test in the book and right off the bat the stator test fails. It’s only got 69/70 ohms on the red to black and red/white to black. Calls for 90-140 ohms. So that fails
Then on the yellow to yellow test it’s just past past the .05-1.9 at 2 ohms. But that flickers and might zero out when holding steady. Not knowing 2 strokes all that great it had all signs of a weak spark. The fact it got much better on wires maybe they stressed the stator out on the last season he ran the boat. It looks to have one cd box replaced as one is different. So looks like not much actual maintenance just replace as it failed.
At least the compression is strong and very much the same on all of them so I can live with some electrical parts for sure.
So my question is now should I just replace the stator? Or do the other parts under flywheel when in it? I have it apart it’s got some rust on the stator but looks like a knock off as don’t see any Mercury Id on it.
Which leads to next question aftermarket stator or oem only? I think I saw Mallory makes ignition parts for this motor possibly. Their car stuff is really good used it on older muscle cars for years. Or just go oem? Of course I look at Amazon and so many knock offs mixed reviews.
I just don’t want to over pay on anything so looking for advice.

As for fuel pump it was blown out as was mentioned to check. I got an oem kit for it and only came with one diaphragm with no holes and one with holes for a stock oil mix setup. Whoever did it put the rubber check valve then plastic over it so one rubber was folded over. Then one gasket on the feed side was split in the middle of it. So probably didn’t work and or dumping fuel. I re used the rear diaphragm and put the new one up front. I guess one chamber is for mixing ? The rear was actually the only part still ok. But the rest is now new.
I’ll leave that lift pump if runs ok with it. As stated maybe it’s a lazy mans primer bulb. Lol here a picture of it maybe something will recognize it.
Thanks for all the help so far you guys are life savers really. Won’t order anything until a few of you comment.

 

[Faztbullet]

Need to test stator with a DVA meter for voltage output due to ohms will change with temp,meter type,leads and if touching with fingers. Also that the high side of stator and only effects ignition over 2000 rpm

 

[Lt1z350]

Need to test stator with a DVA meter for voltage output due to ohms will change with temp,meter type,leads and if touching with fingers. Also that the high side of stator and only effects ignition over 2000 rpm

I used both my cheap 50 dollar meter and my expensive fluke both come up with below spec ohms 60 degrees today maybe a little warmer in the shop.
I also did a spark test and it’s not even enough to light up a cheap spark tester that on my Camaro with a 45k coil goes so bright I thought the bulb will pop. I believe the marine is a 40k coil and I’d expect that it should at least show like an old flashlight bulb when spark hits and it’s so weak on cranking it’s non existent. At dusk it almost isn’t lighting the bulb enough to see it.
But if the stator isn’t affecting crank and or idle spark strength what else in this loop is not working as it should?
As for the wires they are a no ohm solid core race wire that Is shielded. I just used them as had them and no one local had anything though I’m in Dandridge and have lakes all around me. The pre made marine wires had some pretty poor reviews so very hesitant to order anything but oem or make a new set using solid core stainless like moroso makes still for a racing only application or maybe marine like Mallory. For now I’ll continue to try these as was so much better once I was over 3k rpm. Still not right but better. I can hear the cylinders cut in and out but seems to be firing enough now to get heat in all cylinders as I checked with a temp gun.
Reading the plugs even on two that fire enough to make a difference when pull a wire off at idle are not burning well. All of them are some what wet just like not enough spark and only the two strong ones show a carbon track from the electrode to the plug side as these are those weird shielded no strap style.
As plugs come out wet this all adds up really.

 

[Lt1z350]

Outboard spark plug wires have stranded stainless steel conductors. Do not use resistor wire as used in autos.
You can search for aftermarket custom fit from Sierra or others, or use OEM. You can make your own, with new springs, boots etc., however, I would buy them premade, to eliminate any issue with them.

I would like to see that lift pump. I never saw one as described.

All marine fuel tanks pull fuel from top of tank. Bottom tank fuel supply is inherently dangerous as bilge fills with fuel if a leak occurs.

Fuel tanks have anti siphon valve. Maybe yours is clogged?

Here is that pump

 

[Dukedog]

you don't need tha mechanical pump when ya have tha electric pump.. it can be by-passed and/or completely removed..........
is tha 'lectric pump fired by a relay or jus by a "switched" hot?

 

[Faztbullet]

You cannot test spark strength with a "neon anything" Need to test with open air gap tester and minimum 3/8 gap to be jumped.

 

[Chris1956]

That electric pump is an add on. Likely to fix a mechanical fuel pump "lack of maintenance" issue. If it is wired to a relay which turns it off when the motor stalls, with the ign on, it may be safe. If not, it is pretty dangerous.

Let's say the fuel pump is wired directly to the ignition and the fuel line breaks, and you don't realize it. The motor stalls but the electric pump keeps pumping. Where does that fuel go, while you are trying to restart the motor?

I would recommend you rebuild the mechanical fuel pump and disconnect the electric one.

 

[Lt1z350]

You cannot test spark strength with a "neon anything" Need to test with open air gap tester and minimum 3/8 gap to be jumped.

So it’s different then a car where it needs way more voltage as some of these motors are 10.5 compression and have a supercharger on it?
A 40k coil should light a 12v bulb very easily. I used these on dirt bikes when younger and remember they would test the spark same as a car. But I’ll go do an air gap test my bet is that not all plugs are hitting the same as two cylinder seem to fire better at idle then it all cleans up a lot in higher rpm.

 

[Lt1z350]

you don't need tha mechanical pump when ya have tha electric pump.. it can be by-passed and/or completely removed..........
is tha 'lectric pump fired by a relay or jus by a "switched" hot?

It doesn’t come on until engine is cranking. Key on it doesn’t pump as tried to use it to drain the tank but didn’t start pumping until I was cranking the engine.

 

[Lt1z350]

That electric pump is an add on. Likely to fix a mechanical fuel pump "lack of maintenance" issue. If it is wired to a relay which turns it off when the motor stalls, with the ign on, it may be safe. If not, it is pretty dangerous.

Let's say the fuel pump is wired directly to the ignition and the fuel line breaks, and you don't realize it. The motor stalls but the electric pump keeps pumping. Where does that fuel go, while you are trying to restart the motor?

I would recommend you rebuild the mechanical fuel pump and disconnect the electric one.

 

[Lt1z350]

I see your point but seems to be on a relay as not on until cranks. I have been replacing all the hose and putting clamps in it not zip ties trying to make it as fail safe as possible no matter what pump is being used.
So I rebuilt the mechanical but here is my question. It has two ports coming off it. One goes to upper carb and one goes to the actual intake I assume something for the oil injection.
How much of that can be removed and capped now with it bypassed? This thing has so many smaller lines that come off the cylinders I guess to pressure the system? Most of them seem to go from the cylinder to the intake like it’s pumping air from the cylinder into around the base of the carbs. Does anyone remove and cap all that or just leave it? I just worry about how some of this other stuff was done that it might not be correctly run or half assed as I don’t know what I’m looking at for it to be hooked up correctly and not leak or push into something it shouldn’t be. I tried to find a schematic of some sort and even the book doesn’t lay all that out and can’t find much on bypass of the full system. Just worried a leak in that setup will cause issues so like to remove it or make sure it’s correct.

 

[racerone]

??----Your motor has a fuel bleed system , they are the small oil lines.------And it also has an oil recirculation hose from bottom of the block to near the top bearing.-----The fuel pump has hoses going to it for PRESSURE pulses from the crankcase.-----Those pulses operate the simple pump.------Oil is injected into the fuel line before the pump and carburetors.-----Make sure you fully understand before starting this motor.-----Mistakes might lead to expensive repairs !!