1997 Mercury 150a

[Worm0129]

I have just purchased an 18ft Xpress with a 97 Mercury 150. Compression tests show: 121/115/119/115/111/116 top left to bottom right. At 1700 rpm it starts to lose power. I can push the "choke" on the key several times to get it up above 2000 rpm and then it will run fine up to 4800 rpm WOT. Prop is QA2014X 18p. I realize WOT should be higher rpm and that may be the prop size, however, until I get it running smoothly past the 1700 rpm there is no reason to look at prop size.

I had a local shop (part time boat motor mechanic) check it out because it would not idle. He "removed & cleaned the top carb" because there was spark on all 6 cyls but pulling the wires off the top 2 didn't effect how poorly the engine idled. After the carb cleaning, it idles smoother although still dies sometimes.

Do I need all 3 carbs rebuilt? It doesn't have the oil injector (removed by previous owner) and I have fresh gas oil mixed 50:1 with a can of Seafoam in it. Before going back to any mechanic I'd like an idea of what the problem might be. I can't find a serial number, but it appears to be the MERCURY > V-150 > 0G303046 THRU 0G760299 (USA)

Thanks.

 

[Bill kubiak]

Compression looks to be decent, but it would not hurt to have a look in all the carb fuel bowls to what if any thing is in there besides gas. Carb rebuld is easy and fairly cheap.
Here is a little trick I learned from an old Outboard Mechanic to make a sluggish engine run better. get can of seafoam put it in something like a squirt bottle, fire up the engine with the hood off and you have access to carb throats run it around 1500 rpm and let it warm up and then start squirting seafood in all the carbs and keep going until the engine finally bogs down and quits and then let it sit for about 15 minutes. Then fire it back up, CAUTION there will be a lot of white smoke as all the carbon and seafoam residue is burned away this will take several minutes before the smoke stops, you got a 50/50 shot the engine will run better, you might even have better compression

 

[Worm0129]

Thanks. I'll give it a try tomorrow after the auto parts store. Good to know the carb rebuild is simple. I never got all the parts back in place in my 4 bbl in high school shop. Now I've done most of my automotive work myself, but I'm still leary of carbs.

 

[Bill kubiak]

Boat carbs are simple, very few parts, you need carb cleaner and air pressure to blow passages clear, just hard to remove and re-install and while your at it change the rubber fuel hoses, I just found that my hoses are rotting from the inside from the ethanol gas.

 

[Ant-Knee]

Hello There,

This sounds like the same problem I am having, Please click on link below and watch video,




http://forums.iboats.com/forum/engi...board-150-midrange-issue-watch-video-plz-help

 

[hunter200524]

If you can do a leakdown test. those compression numbers sound weak. A leakdown will tell the true tale. Even better if you have a bore scope to look in the cylinder. If the motor is now running on all 6 cylinders, i would be looking at the fuel pump diaphragm. If it has black paint on it still it has never been replaced and would be a good place to start.

 

[Worm0129]

Bill K, The Seafoam worked. It now comes in a spray can. Bought 2 cans, staled the motor 3 times and let it set for 20-30 minutes each time. Took the boat out yesterday and it ran right up through the stall point. After about 2 hours of running the motor off & on, it started having the same problem, just not as bad. I think I need to tear down, clean & rebuild the carbs. Also, I'm thinking the motor is older than I was told. The carbs are WH 1374-5427-C 157-155. I find on this forum they were used on Mercury motors until 1984/85. Air intake cover is like that time frame as well. The cowling is from 1997, so I'm not sure what I have.

Do you recommend more Seafoam or just rebuild during the winter? I'm in Iowa and it is difficult to boat when the water is solid...good time to do maintenance.

Thank you for the help.
Bill

 

[alanfox55]

I have a 97 30hp with one carb I was having a problem with that seemed to be a dirty carb. I cleaned,rebuilt,cleaned,adjusted,cleaned some more then I got some Yamaha carb cleaner and soaked it. Don't know for sure if that's what fixed my problem because I did a few minor things too but it sure seems like that was it...it's running great now.

 

[Dukedog]

No Title

The carbs are WH 1374-5427-C 157-155.
Bill

wh's went from '76 ta some '90 models.. they went away when tha block changed in late '90..after block change they are known as a "fat block" and/or 2.5 style block even though they can be a 2.0, 2.4 or 2.5.. they all have wmh or wmv's... look on tha top for a wh ? number stamped in tha flange casting.. some will have it and some won't.. look for a build date stamped at tha base of number 2 cyl. where tha block halves split.. kinda behind tha bend in tha advance arm in tha picture below.. 1/8" numbers.. m/d/yr.. may be hard ta make out but its there.....

not kosher ta rebuild ONE carb......

 

[Worm0129]

No Title

Here are some pictures of the date stamped in the motor. March 24, 199x? Also some of the motor parts & carbs. Any help deciding the date of manufacture would be great. It has a 25 inch shaft, too long for my boat.

 

[Dukedog]

there is something really outta kilter with that motor... that chargin' system went away in '89 'cept for some 135's.. WH series carbs went away in '90.. tha heads, from what I can see, look ta be earlier pre lost foam ('88) 2.0, 2.4 style.. may even be first generation motor?.. can't really tell in those pictures... need pictures of heads and port side of motor....definitely NOT a '97 150......

look here for a serial #.. its on top of tha block... .

 

[Worm0129]

No Title

Dukedog, more pictures of motor. I'm calling it a "Frankenst-ercury". Some pictures are of part numbers. No freeze plug on top or any serial number I can find. Hard to decide what to order for parts if I need them. Other than tearing apart the motor and measuring cyl. size, any ideas of how to tell what size it is?
Yes it is painted a red color. The 2nd owner of the boat wanted to match the color to the boat graphics. I just want it to run right.

 

[Dukedog]

tha latest year for that motor will be '82.. looks complete and original.. its first generation motor ('76 ta '82).. 99% its a 2.0 liter motor.....

 

[Worm0129]

If it is from '76 to '82, why the date of 1993 on the block? I agree that it is from 1979 because of the March 24, '9 on the block. What HP is the 2.0 liter? Any place else I can find/look for serial number?

 

[Dukedog]

few years ago we got one in with a build date of '96 but was actually a '76 so it does happen......may be a '79?.. stamped ona "hang over Monday" or "hurry up happy hour Friday"???

doubt there will be a serial number anywhere else.... could possibly be a 175 or 200 but doubt it... '80, '81, '82 225/200's were 2.4 but have horizontal front halves .. if you can find a WH XX (number) stamped on any of tha carbs it would tell... other than that ya gotta pull a head which is not recommended (on those blocks) just ta look.....

don't remember for sure on first gen. motors but tha heads MIGHT have a small stamped circle with either 3 1/8 or 3 3/8 stamped inside tha circle.. it will be on edge inline with tha head bolts...

 

[Worm0129]

Dukedog, I'm back again & still working with the carbs. Had other things on my list and didn't get to the boat until 2 weeks ago. I bought 3 gasket kits from iboat and a can of carb/parts soak. I've been doing 1 carb at a time and notice that the jets are different size. The carb is an 18502 the parts list is here: *****************/parts/mercury-outboard-parts/v150/4868998-thru-0a904645/carburetor-assembly. (Marine Engine . com)
It looks as if #10 Jet, Main Fuel, I have several (.064, .066, .050) and #20 Jet Main, Idle Air Bleed, I have (.044, .046, .050).

I'm down to my last carb and wonder if I should spend the money to make them all the same. If so, what should I put in? Why are there different ones available? I also found some of the plugs #8 and #18 had 2 and 3 gaskets on them from someone else "repairing" the motor.

I have also bought new fuel lines as some of them are not tight on the nipples, even with clamps.

Thanks for any help you can give.

 

[Dukedog]

think yours will be wmv's.... on tha linkage side, carb body there are some numbers... need ta know those... all mains same size, all idle same size, all mid same size...

all hose bibs should be same size... sounds like they been shade treed!

 

[Worm0129]

1374-5427-C part number of body? Top carb 34-13097, middle carb 34-23097, bottom carb 34-33097. Those the ones?

 

[Dukedog]

here is all tha stuff on carburetors... may have ta copy n paste if won't open on its own... donno how its gonna show up...

http://www.corboatracing.com/downloa...ury-manual.pdf

 

[Worm0129]

Sorry, that is not the carb. Mine has 2 floats. I'll try to send a picture. Mine is just like this one.