Need Ideas/Help! -- Intermittent Mariner Mag (XR2) 150

[mattyc]

’87 Mariner MAGNUM 150. I believe this motor is pretty much an XR2.

The motor was bogging down out of the hole and generally running sub-par. Took a peek in the main jet hole and the carbs looked like they had some crap in them. So I tore down the carbs and cleaned them up last week and was waiting around for a rebuild kit that never showed up. Kit is supposed to be here on Monday. I had Sunday cleared with the wife to be on the water. So, I ran down to the dealer and got the gasket kit and put the carbs back together. Timed and synced it. (Timing was really confusing in the Seloc book… I ended up going 11ATDC for idle and 22BTDC for WOT) Note – new fuel pump diaphram kit, new fuel filters, new fuel lines.

Well, for the first 15 minutes she ran better than she ever has. Lots of stops and starts to check the hole shot. Then, it started running really crappy. Could hardly idle, and when I’d get on the gas it would kill. . Plugs all looked the same – fine. Messed with the timing but that just didn’t help. It got to the point where it wasn’t even firing when I was cranking it. Checked for spark on each with the timing light, and they all had spark. Then, it finally got up and ran to the other end of the lake like a champ. Basically out of nowhere.

Well, we fished for ½ hour, then it wouldn’t start worth crap – did the same thing. Not even firing. The bulb was hard. The fuel pump was pumping fuel. Dinked around for 5 minutes and then it started running good again. Even went through this process a third time tonight.

Can anyone give me some ideas here? My best guess is that something is stopping my fuel flow – one of my carb needles not seating or getting stuck…? But if this was the case, I would think that it would still fire on the rest of the cylinders… FYI -- I ohmed out the trigger and it looks fine.

Thanks!!!
-Matt

[mattyc]

Just a note: I only put the gasket kit in. I did not do a full rebuild on the carbs.

Also, when this thing was running crappy and then coming out of it and running fine, I was NOT changing the timing.

I'm hoping to get on the water tomorrow night. Does this sound crazy... I'm thinking about bringing a rubber mallet and tapping the carbs if this happens. See if I can un-stuck something...?

[sho305]

:confused: How about tank vent/pickup, sucking air into fuel, bad bulb? You think all cyinders/carbs were doing it or just enough of them to kill it?

Otherwise I have had of plugs and triggers do that mystery thing.

[mattyc]

I hadn't thought of the vent. I'll check that this AM.

I think all 6 were doing it because when it was at its worst, I would sit there and crank it over and it sounded like none of the cylinders were firing.

[mattyc]

When I took the fuel pump/carbs apart, there were zip ties on the fuel lines everywhere they were attached to a fitting. I didn't replace the zip ties. Anybody think that could be enough to suck air and cause problems?

[sho305]

The fuel, would suck air before pumps and leak after I would guess. I had a bulb that worked, but it filled my pumps with rubber bits. It was real old I think. I had others that a valve in there was hanging, and would plug the line at times. Depending on your setup; with mine I could take the motor fuel connector off and lower it, then take a wooden match/clean stick and open the ball. The fuel would run right out by gravity then so I knew there was no restriction. I let it run for a while to check the air vent, into a bottle. With that tank I had taken it all out and apart, but then I knew for sure I had good fuel to the motor cowl. You can also test try a different tank/hose from another boat. If the whole motor is suffering, I would guess you are right with a fuel supply problem (not one carb/etc), second possibly an electrical problem affecting the whole ignition intermittantly (but that does not look likely yet).

Most carbs I just take apart and clean, unless I have a bad float or torn gasket I don't replace anything but filters and the gaskets sometimes. Or I do it when I get it, then they are good while I have it. I find it easier to put a little fresh premium in there every year and run it in the yard for a while, maybe a gallon (er, and I like to hear it). With my inline I put a squirt of carb clean in the float plugs/main jet before I start it, but it stays clean in there long as I don't go over a year. Over a year I think it better to drain it all good.

If the hoses went on harder, they should seal good as that is not a high pressure fuel system. But as they relax I would not trust them to stay...zip ties are cheap. Are you sure the fuel pumps got put together right? They could do it, though they are pretty hard to get screwed up.

Plugged tank vent often sucks the bulb flat, but not always. Due to it being such low pressure it may not take much to screw it up. Some bulbs are harder too. Could also be water in fuel tank. I had problems with that on stuff, so I like to put a little carb/injector cleaner in the first tank with a little extra oil. That for a stock motor anyway.

[mattyc]

Yeah, I know... I'm posting more on my thread than anybody!!!

I was just out looking at the vents and they are fine. What I did notice was the fuel fittings on the bottom of my carbs. I used blue loctite when I re-installed them. The loctite oozed out a little bit, which was fine. But now there is no ooze -- it looks like it's been cleaned away by gas. (Suggestions on what to use???)

If my seal has been compromised at the carbs, that should just be a potential gas leak, right?

[Bill Rogers]

Matty - it's not overheating is it? Sounds like you're describing a vapor lock condition. With the pump mounted to the block, if the motor's hot, the fuel pump's hot too.

Do you have an anti-siphon valve at the tank? How about a filter between the tank and the engine? Any kind of a restriction on the suction side of the pump will make vapor lock more likley.

I'm with Sho - doesn't sound electrical (not yet anyway).

[mattyc]

I don't think it's overheating. I was handling the spark plugs a few minutes after WOT runs, and they were warm, but not too hot to touch... The fuel pump is on the front of the engine anyway, and shouldn't get very hot...

My fuel delivery system: Gas tank has a sealed gas cap, second line come up to a vent. The fuel line to the motor just has the bulb inline and then plugs into the motor fuel receptacle (have people had problems with that receptacle???) From there, it's into and out of the fuel pump, through a (new) in-line filter and to the top carb.

I'm going to be on the water tonight. If anyone has any ideas of what I could try that would be great. If I get into this condition, I'm first going to check the bowls to see if they have fuel in them. Then I'm also going to check that the fuel pump is pumping fuel.

[Bill Rogers]

The anti-siphon valve (if it has one) is the fitting on the tank the hose attaches to (looks like a regular barbed hose fitting on the outside).

[mattyc]

Looks like it was the primer bulb. After having all the problems on Sunday night, we went out on Monday night and every time it acted up (4 or 5 times in 2 hours) we started squeezing, whacking, and beating the crap out of the primer bulb. Every time we were off and running again. The thing about this bulb is you could just keep pumping it -- it never got to the point where you just couldn't squeeze it -- I guess I hadn't paid enough attention to my bulb. When I took it off I could actually blow backwards through it a little even when the ball was seated. I need to take a real close look at the bulb to see if there was a puncture or crack of some sort where it would have been sucking air...?

We were on the water with a new bulb last night. 4 hours and no problems.

I just put a new bulb on last year. Cheap $5 Attwood I think. I put the same cheap bulb on again. Does anyone know of a really good high quality bulb that won't cause me any more problems?

[sho305]

That is great if you found it. I have heard of Merc bulb/line sets, don't know as I think mine is an Attwood also. I have had them work fine and still hold back fuel, just never know with them. That is why I took my tank out and held it up to see fuel come out of motor gravity, a hassle with the screwed in tank. Then I know I have full flow all the way through.