'92 Mercury 150 XR4-Hard to start, low idle, dies

[Toxarch]

I have a 92 Mercury 150 XR4 BlackMax. One of the POs installed a hot foot and apparently disconnected the fast idle lever and choke. Or at least that is what it seems like to me. I know the fast idle lever does not work.

When I try to start the engine, it's sometimes hard to start and won't fire without pushing the pedal down a little. Once it does start, it idles really low like down around 400 RPM. It will also sputter out and die idling that low. I can give it a little gas to keep the RPMs up a little, but even then it's like it bogs down and dies. It even does this after the engine has been stopped for only about 20-30 minutes. I have to start it 5+ times to get it going.

Once the engine has been run, it will idle fine at around 800 RPM or so, but the engine has to be run to get it to do that. I can give it more gas when out of gear (if it doesn't bog down and die first) to get the RPMs over 1000 for a little while and then it's somewhat OK.

I'm guessing I need to rebuild the carbs. But figured I would ask here first. I'd really prefer to wait until winter to rebuild the carbs if possible. I know when pull starting, there is supposed to be an enrichment button pushed in (same as choke I assume). Any clue where that button is? I might have to see if I can figure out if the starter's choke is still connected or not for sure.

 

[sschefer]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

When the hot foot was removed the pre-load on the throttle cable might have changed. That could effect initial timing. Get a manual if you don't have one and do a Link and Synch. If that doesn't solve the problem then perform an electrical system check. If it's not there then look at the fuel system.

 

[Toxarch]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

The hot foot pedal is still installed.

I have a Clymer manual. I'll look through there and see what I can find.

 

[sschefer]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

The hot foot pedal is still installed.

I have a Clymer manual. I'll look through there and see what I can find.

Oh, I misread.. sorry. Still that is the place to start.

 

[Toxarch]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Turns out the choke is still connected. I can hear the click when the cover is off.

I pulled the cover off today and noticed some oil had dripped out of the upper reservoir. Don't know how since the cap was secure and the hoses appeared to be OK. but there was oil sitting in the grooves on top of the carbs. Opened up the reservoir and it was a little lower than usual, but still had plenty inside. You can see some of the oil pooled in the round thing on the right:

Found a cut hose leading into the engine. Followed the line and it appears to be the air pressure line going from the crank case to the oil tank in the boat.

You think that split air pressure line could have something to do with the hard start and the oil leak from the reservoir tank on top? I have found that if the tank is tilted up, then it starts right up, but if tilted down, then it's hard to start it. I wonder if it closes up the cut in the hose when tilted up and that helps is start and run. I imagine that without that air pressure going to the oil tank, it's going to have a hard time getting oil up to the engine to mix with the fuel.

You think I can just use a hose butt splice in there and be fine or do I need to replace the entire hose?

 

[j_martin]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

The oil reservoir on the engine is supposed to supply oil for about a half hour running at WOT if something fails in the supply, like a cut line.

There's a 2 psi check valve that it overcomes in the T before the tank. That valve seldom operates in normal use, and might drip some oil if actuated as it would have been.

After you repair the line, run the engine and crack the cap on the engine reservoir until it's plumb full and overflowing. Then tighten the cap, but don't get carried away. They split if overtightened, and are expensive.

None of that has anything to do with hard starting.

Normally, on a cold start you have to fast idle it till it warms up, which usually only takes about 20 or 30 seconds. The fast idle operates the throttle cable directly, so if a Hot Foot is installed, that would be disconnected.

You, sir, are the fast idle mechanism in that boat. You just have to throttle it till it warms up.

hope it helps

 

[sschefer]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

You, sir, are the fast idle mechanism in that boat. You just have to throttle it till it warms up.

Yep, most of these mercs need a little help waking up when you kick em the first time. Do fix that air line though, that's not something you should wait on.

 

[Toxarch]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Thanks for the replies. I have been having to use the pedal to start the engine so I guess that is normal. But there is still the idle problem when warm. I can run the engine, slow down and then idle in gear or even out of gear and the boat just dies. Is there an idle adjustment somewhere so I can up the idle RPM a little?

Quick question about the oil. Do I have to open the cap and let it fill itself or can I just open the cap and fill it myself?

Any idea on a part # for the oil tank lines? I tried searching iboat parts and even googled, but couldn't find anything. Think I can find some at the local boat repair shop?

 

[sschefer]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

First get that hose fixed, the part # is 99439 @ 61.30 each from Mercury. You can order it through Crowley Marine.. http://www.crowleymarine.com.

If that doesn't help with the idle problem, check your initial timing. There is a lot of room to play with in this setting for this engine. If you advance it slightly your idle should improve but the trick is not to exceed the recommended idle speed or it could make the engine difficult to shift.

The carbs could be the culprit also. If you haven't played with any of carb idle screw adjustments and you don't think anyone else has either then you may want to run some Merc Quick Clean in the fuel to see if it clears the problem. If that doesn't work you can do a full Decarb with SeaFoam.

My personal recommendation is that you take it in for a full service including a link and sync. If you've had "hands on" time with 2 stroke engines then you can easily do it yourself.

The only reason I say the above is because a link and synch if done improperly won't just make your engine run badly, it can destroy it.

 

[j_martin]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Thanks for the replies. I have been having to use the pedal to start the engine so I guess that is normal. But there is still the idle problem when warm. I can run the engine, slow down and then idle in gear or even out of gear and the boat just dies. Is there an idle adjustment somewhere so I can up the idle RPM a little?

Quick question about the oil. Do I have to open the cap and let it fill itself or can I just open the cap and fill it myself?

Any idea on a part # for the oil tank lines? I tried searching iboat parts and even googled, but couldn't find anything. Think I can find some at the local boat repair shop?

You can fill it up mostly to save time. The loose cap procedure proves the delivery from the boat tank, so that's the way to go.

The oil system components, including tanks and lines are listed in a parts list for your engine. Here's one for my XR4, probably the same.

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=%2018739&ivar=images/COMMON/18971.png&inbr=370&bnbr=190&bdesc=OIL+INJECTION+COMPONENTS

To the moderator gods of this site, I could not find the part on Iboats.

You can also cut and/or splice the original hose. There's nothing unusual about it except oil resistance. Pressures are around 2 psi.

On the idle issue. Being it's new to you, and if you wish to learn about the engine and do it yourself, get a mercury maintenance manual. The part number for it will also be in the list. usually they are NLA, but you can find them on eBay or other places.

Then do a compression test to see if it is in good general health.

Then check the bleed line routing and check valves. Anything amiss there will hose your idle and not affect anything else.

Put a clear piece of hose (cheap vinyl hardware store hose) in the fuel line between the bayonet and the oil mixer. Idle it on cuffs and look for bubbles. Fix any fuel suction problems you find.

Then do a link and sync. Quick adjustments that seem to work done by the PO's may have put it out of step. It's critical for both performance and longevity of the engine. The L & S sets all preliminary spark timing and linkage progression and synchronization.

Troubleshoot any other problems found, such as a miss, or flooding carbs.

Then put it on a lake and set the idle.

Hope it helps
John

 

[Toxarch]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Here's a progress update.

Rather than fixing the hose, I decided to repair it since it's just a 2 psi air pressure line. I cut the hose the rest of the way and then installed a 1/4" brass hose coupler. Checked the part holding the hose and it seems someone put the two pieces around the hose and wires in wrong. The lower piece was installed backwards so it pinched the oil lines and caused one to split. I reinstalled it the right way.

Started it up, bled the air out of the reserve tank on the engine and the oil appears to be pumping through great. Engine appears to be running a little better too. Maybe the oil suction was causing a fuel flow problem.

Warmed the engine, then pulled the plugs, shorted out the plug wires to ground, and did a compression test. All the compression numbers appear to be good.
(1)113 (2)119
(3)118 (4)118
(5)120 (6)113

The existing surface gap plugs still looked good so I reinstalled those.

I read through the Clymer manual link and sync instructions. Seemed like something I could do if I had something to measure the RPMs accurately and had easy access to a boat ramp to use for a while. I might have to pay the mechanic at the local marina to do this for me so that I know it's done right.

What does a link and sync usually cost?

 

[Toxarch]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Oh yeah, I opened up the breather cover and there is no filter in there. This is my first outboard, but I'm pretty sure it's supposed to have an air filter, right??? I tried to find a filter part number in the manual but can't find the air filter mentioned in there.

 

[sschefer]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Nope, no filter. You rarely run into dust storms on the water. Not sure on the cost of a link/sync I always do them myself. The first time through is not hard but there are some tricks you'll learn after the first couple of runs. I just broke down and paid 250.00 for a timing light with all the bells and whistles. It has a tach and advance/retard built in so all I have to do is verify TDC and point at zero. And the light is super bright so there's no problem seeing the mark in bright sunlight. It's so much nicer than my old cheapo. You can rent one almost like it from Kragen's/O'reily's.

 

[xxturbowesxx]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Do not attempt to do timing with this motor without buying a manual.
The xr4 motors are unique and have a advance/retard module on the motor. It advances timing at 5000rpms and retards it at 5500. If you simply set the timing to spec on a 150 then It will advance that number and may damage your motor. I personally removed the module and set the timing to 150 spec for safety.

I have had 2 xr4's and this is my process. You seem to have a fair amount of knowledge but if it helps. You need to prime your bulb from the gas tank until firm. turn key to the on position(not start) then press the choke for about 8 seconds then turn the key. It should start then use your hotfoot to give her a rev or 2 then she should run great. Also I would suggest removing all the oil injection and premix.

If not you need to trace all your fuel lines to make sure they are not obstructed and also remove and check your carbs. If that doesn't solve your problem at least you can move on. Then I would purchase a timing light and set the low speed timing(controls idle speed).

So go out and buy a good manual for your motor and use the internet for sources. I use Iboats and you may want to try screamandfly forums because your xr4 is a high performance motor and commonly used in that crowd.

 

[sschefer]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

Absolutely correct about the timing. My V-135 has it too but it's not going back on after the rebuild. Merc must know it's a bad idea because it doesn't even show up in the revised parts manual. Sort of in the class of things like the water cooled voltage regulator on top of the exhaust cover. Now that's a concept!

 

[Faztbullet]

Re: '92 Mercury 150 XR4-Hard to start, low idle, dies

A air leak in hose will make that cylinder(#5) run lean and thru idle crappy. Also this engine has the WMH carbs that use a thermal air valve on starboard cylinder head, this restricts air flow to idle circuits thus richening engine untill temp is above 100degrees. If it is bypassed, stopped up engine will be hard starting