1988 xr4 150 issues

[adam98]

Re: 1988 xr4 150 issues

Thanks for the insight, yes I have an aftermarket manual. And I noticed if I squeeze the fuel bulb firm gas will travel back up to my oil resivor..Not good. But im sure once running the take has pressure and will not back flow. But the this 42425 1 valve is obsalete? I see 42425 but that's for the oil side and I'm sure that has a stiffer spring. Also the carbs are incredibly simple and lack adjustments but that's a good thing. You can see through every hole and access them directly. Spec says 1mm higher then body for floats but I put them a 2mm as I wanted to richen them up but will reset the floats again at 0mm

Also if I use the warm up idle control to rev it up in neutral on the lake it really sounds like its knocking and pre detonation.

Also it idles way high at 0* idle timming and I'm at -8 to get a 1k idle

 

[adam98]

Re: 1988 xr4 150 issues

Ok just rebuilt all carbs again and checked reeds. I set the floats to 0mm and found the lower carbs were at 3mm. Must of been late. Ill get it on the lake in the morning and report back

 

[DamianJP]

Re: 1988 xr4 150 issues

Check all the jets in the carbs too.

Be careful they are brass. %100 tight fitting flat head to back the jets out.

Also double check what carbs you have. I know you can play with different carbs and jets , I say stay stock if ya can if your not racing.

Stock carbs for 1989 XR4 is .... (Thanks to Jmartin)
WH41
Main .074
Idle .052
Vent .076

WH41A
Main .074
Idle .048
Vent .076

The only difference is the A set runs idle slightly leaner.

On mains, larger is richer
On Idles, Larger is leaner
On vents, Larger is rich sooner.

Check this thread out , should help.
http://forums.iboats.com/mercury-mariner-outboards/mercury-carb-questions-325453.html

Also Im surprised Jmartin didn't chime in yet , he's a XR4 guru.


This motor and problems I bought it with is what got me into outboards.The Mercury XR4 is a bad b!tch. I will never sell. Sounds like your into outboards too, treat her nice or sell to me. J/K !!


Hope it helps and keep us posted,
DamianJP

 

[adam98]

Re: 1988 xr4 150 issues

Awsome. Thanks alot, i started feeling lost and fustrated. as I prob. know to much for my own good sometimes. This boat and motor are extremely low hours and every bolt on it was untouched before. Just sat to long.

I think my carbs are in need of a gasket set...
Oh and the check valve on the oil fuel feed line....Mine does very little for locking out back flow. If u were to blow on yours would it have a good seal to stop back flow? 42425 1 is obsolete but minis the 1 and that's the oil feed check valve whitch it 2psi and that would mean the injustion pump would have to pump 2psi to get oil into the fuel line.. Seemed to "feel" like it was to strong for the fuel side.

 

[DamianJP]

Re: 1988 xr4 150 issues

Just to keep things in perspective the whole ignition and electrical system has been ruled out?
You've checked both power packs
You've checked/replaced stator

1)Is trigger and coils all checked and ruled out?

2)Check linkage(s) carbs and timing side too. Make sure it operates smoothly thru idle to WOT and back down, make sure it seats back fully and the trigger arm isn't returning to it's place because of it not seating back fully.

3)What are you doing to the carbs when you rebuild them?

I'd get the %100 kit , check if your floats are the old material and not the new hard plastic. Needle seats can be leaking and the needles can have a wear ring on the rubber tip. Ethanol hardens older needle rubber tips sometimes and make them hard. Start fresh not just the gaskets.

You are %100 that you have WH41(or WH41a) and jetted to stock specs?

4)I thought there was only 1 check valve and thats on the opposite side of the oil pump side. The other T fitting is just for flow, no check valve(s) on it I don't think. I don't think at any time gas should leak into the oil res. I have limited experiences with outboard oil systems.

He's a good thread about the oil system on this motor... Post 9 will clear up some I think. But read the whole thing.

http://forums.iboats.com/mercury-ma...-oil-injection-operation-question-442843.html



Side Note about my XR4 and my oil probs...
When I first got my XR4 my oil injection check valve was sticking , because it was sticking close and trying to over pressurize my oil tank. Then got a new check valve and it solved my problem but from the beginning I always had no beep beep for the oil system check when key is turned on and got the occasional oil beep beep beep. So I got scared and took the oil pump off. I pre mix 50:1 right now. Down the road I might put it back on. I *THINK* the pump dials the oil back to 100:1 for idle and higher RPMS it goes to 50:1.



Let me know,
DamianJP

 

[adam98]

Re: 1988 xr4 150 issues

Floats are new ones, all offices clean. Carbs were super clean to start with but could use new gaskets. Three times I have reassembled them checking everything. Lines checked and new. Coils checked, timer base checked at wot an idle w/dva, and resistance. Fuel pump rebuilt and pumps well.

Back to my tee question... the tee where the fuel and oil mix is a check valve. It has a sping and cup inside it. If I blow really hard into it it will almost completely seal up. (blow from fuel side up to pump side) but when blowing softly it just stays open and does not seal up and not functioning as a check valve. I only checked it cuz when I prime bulb until firm has will fill carbs up and then fuel will go up tee into oil pump and into the oil tank. This was not the case a week ago. When there was a little air in that line if I really squeezed the bulb the air would not go up the line into the pump and into tank. This is all when not running.
All fuel lines are new but may be I have a restriction in the pickup in the tank. Still flows but fuel but not 100% open. Never has the bb been soft.. There should be no pressure in that fuel line before the tank...also I may burn up all the fuel and remove the big 33 gal gas tank and clean it out. It's plastic. And maybe install a vent shutoff so to not absorb water whe not in use.

 

[DamianJP]

Re: 1988 xr4 150 issues

Sorry I was wrong I guess the Tee on the oil pump side is a check valve. I won't be giving you any more advice on the oil system because my lack of knowledge on the system.

This motor like's it's fuel / oil delivery or else it becomes a paper weight.

What are you remaining symptoms on your XR4? Other than gas in oil?


DamianJP

 

[CharlieB]

Re: 1988 xr4 150 issues

Need to be sure about this fuel/oil issue.

Fuel gets into the oil line between the oil tank and the oil pump ONLY when you pump the primer bulb too hard?

My problem with this is that until the oil refills that line and properly blends with the fuel you will be running the motor too lean on oil and can damage pistons/cyls, crankshaft/bearings.

This must be corrected immediately to prevent engine damage.

A temporary protective measure recommended in all suspected oiling problems is top add oil to the fuel tank. Manually protecting your motor until the condition can be sorted out. If the oiler is working at all you will not damage the motor with the extra oil, it will only cause a bit of smoke and possibly shorten the lifetime of a set of spark plugs..Cheap insurance against a motor replacement.

The primer bulb only needs a firm handshake, nowhere near attempting to crush it as such over-pressurizing the system will cause carb flooding.

If the oil check valve bleeds back at a firm handshake then replace the valve.

 

[adam98]

Re: 1988 xr4 150 issues

Right I only squeeze the blub firm cuz I was thinking I had a lean issue as tapping the choke help get the motor off an idle an up to plane. But made no difference. And when it was on the muffs I saw the fuel going into the oil tank when I really pump it firm looking for bad fuel connections and lines. So I drained and cleaned the tank then let it refill by letting the resivor boat tank refill it.(no it wasn't running) rebuild pump and primed it. Also cleaned the pickup screen in the boat oil tank.


So the lower float hight really helped! Made the motor happy.( Floats level with carbs) thats 1mm less then the manual. Idles really smooth all the way down to 500rpm but 800 was the most consistent setting. Really smooth, felt great.... I have the 41 carb so maybe its to rich off idle. why they went to 41a carbs. I'm at 3000ft and its really hot. All causing some what rich conditions over sea level settings.

BUT... Theres always a but.
Regardless of motors temp. If I stopped for 15-20min or even 45 min and the motor was cool. then tried to start it was really hard to start (i smelt the fuel in the exhaust too) and even when playing with the warm up lever, it was hard to just get it to fire. New battery luckly. Then once it did fire I try d to rev it up in neutral. Then if I could get it into gear before it stalled and tapped the choke it would come to life haul *** and jump on a plane. Stop turn off. Start flawless idle for 5 min and have great holeshot. But if I let it sit 15+ min. Back to a flooded engin so it seemed. Floats looked like new as did everything in the carbs. And I have built at least 100 carbs before.

 

[adam98]

Re: 1988 xr4 150 issues

Maybe air getting into fuel line? But no, Bulb still has fuel in it after it sits. Its Still firm. Hmm. Fuel might be leaking into cyl while I'm fishing.. But seats looked new and didn't stick at all. That's why I pumped up bulb hard to see if carb bleed off pressure but they don't.. only found the check valve tee to be bad. Just thinking out loud here.

 

[Dukedog]

Re: 1988 xr4 150 issues

If ya gotta "bump" tha enrichner ya still have a fuel problem, Justa note. Wh series Merc/Mariner carbs and fuel pumps usually don't like used gaskets after ya take 'em apart no mater what they "look like". Fuel can leak inta tha crankcase through tha fuel pump also.................

 

[adam98]

Re: 1988 xr4 150 issues

Great info, I just picked up 3 sets of carb gasket kits and the fuel line tee check valve. Getting pretty fast at getting these carbs off... I doubt its the fuel pump as gaskets were still soft and if it did leak is would only effect the one cyl.... And these start on 5 cyl fine.

The closest dealer that stocks parts is a good hour or more from home... And when local shops tell me we can order it. I think so can I... And prob save time and money. But If they stocked parts I'd be happy to help keep them around and buy from them

 

[CharlieB]

Re: 1988 xr4 150 issues

lol I'm about 60 miles West of St Louis, small shops anywhere won't have much on the shelf, I don't know if I would pay their mark-up if they did. Freight on a lot of parts makes it easy to get them in the mailbox.

3000 feet should be too rich to require rejet of the mains, but that slightly lower float can help an idle mixture. You just have to be sure which way you need to go as checking float INVERTED the lower float is actually causing a higher float/fuel once right side up.

A lean idle mix can idle perfectly yet cause slightly hard starting and poor acceleration. Without an accel pump these require an excessively fat idle mixture, fatter than best idle in gear.

If your holeshot is great then you must be very near perfect on the idle mix.

ALWAYS use the fast idle lever to start, if it turns over more than two revolutions stop, push in the enrichener then crank again.

 

[adam98]

Re: 1988 xr4 150 issues

Thanks for the great info. Everything helps... Weather I know it or not I want to hear everything you guys have to say.
" a wise man can learn from a fool but a fool can learn from no one" right.
Yes I went 1mm leaner. After the float hight changed and really cranked down really tight the screws on the carb knowing it needed new gaskets. Then it felt like it went from runing on 5 cyl to all 6. Really gave it smooth powerful holeshot and a broad power band at any speed. Enough to go staight to cavitation it I gun it at at Stand still. It's a four blade ss prop with a whale tale. Is that ok?
Also my 88' champion 18' bass boat does about 60 ish buy GPS but I can't imagine going faster anyways unless I was covering really smooth water. Not alot of boat left in the water after 50mph or so. Scary. and the lake I fish most castaic lake CA and most local lakes or resivors have a 35 speed limit around here

 

[adam98]

Re: 1988 xr4 150 issues

Not good the lower end shaft that mates with the power head is about to twist off. No cracks but scary looking. I thought at first the teeth were dented not completely twisted!!!!

 

[adam98]

Re: 1988 xr4 150 issues

So rebuilt carbs with new gaskets and figured I would change my impeller as I start it dry for 15sec. Up to 1 min. Before when working on everything. And my water pressure is 2-5psi up to 8-10psi max. But it looked fine. But I changed it and saw this... No cracks but yikes!!! Twisted the 1" rod a good 1/16" is this common? And if it broke I doubt think it would take anything else out, right? But I'm sure it happened when I started it in neutral with idle lever up and it fired instantly to 4k rpm and slammed in to gear 3 times in about 1.5 sec as I reached over to push the idle arm down fast as I could. It was in neutral but obviously not adjusted right. It was a bam.. Bam. Bam. I was worried about the xr4 lower gears not the input shaft twisting off! If this thing doesn't run great in the morning it getting sold!

 

[CharlieB]

Re: 1988 xr4 150 issues

Never, NEVER start the motor without water. The impeller will begin to melt within 15 seconds.

Start looking for a vertical shaft as that one is running on borrowed time.

You may have contributed to the twist but usually that is caused by airing the prop and the sudden shock of the prop regaining bite at high RPM. Like hopping across a wave and the prop gets loose.

Run it carefully until you get it replaced, you'd hate to be stuck out on the water and NO WATER pump when it fails, you could toast the motor very quickly. If ever it looses thrust like falling into Neutral, SHUT IT DOWN immediately.