Hard to start after carb rebuild

affa · Oct 26, 2003

Hello I have rebuild my mercarb on my 140 mercruiser and now it is difficult to start the engine when its cold. When it finally starts and becomes warm it runs better then ever. Earlier I had to pump full gas 3-4 times and it started at once. I have done all the measuring and settings that where required. Affa

Colorado Boat Nut · Oct 26, 2003

Re: Hard to start after carb rebuild

Check the Choke wind it a lil tighter that should help

affa · Oct 27, 2003

Re: Hard to start after carb rebuild

Thankyou, it looks like that helped, but it does not start as easy as it use to, it sounds like it get to much gas, any idea? Affa

CRT Skiff Crafter · Oct 27, 2003

Re: Hard to start after carb rebuild

Hi Affa. I'd recheck the idle jet adjustment. Regards, crt.

affa · Oct 27, 2003

Re: Hard to start after carb rebuild

Hi, and thanks. I was not sure how to adjust the idle mixture, I run the engine on 550-600 rpm and adjust it so the engine run smoothest, is that what it ments? That was only 3/4 turn out, my old setting was 1,5 turn out, and the instruction in carb kit said 2 turns out. Regards Affa

CRT Skiff Crafter · Oct 28, 2003

Re: Hard to start after carb rebuild

Hi Affa. Yeah, that adjust procedure should get it done. I have experienced a change in how far in or out the idle screws want to be after a rebuild, but not sure what is really normal. I hope you get to the bottom of your problem soon! Regards, crt.

Bondo · Oct 28, 2003

Re: Hard to start after carb rebuild

It Sounds like you May want to recheck the Float Settings again......You Might be over filling the bowl.... What Color are your SparkPlugs ???? If you're running Rich, You've got to find out Why..... About a turn + 1/2 is about where you Should be.... What happens when you Pump the Throttle Now, like you Used Too.???? Now that You've, " rebuild my mercarb on my 140 mercruiser ", You've got to Tune it..... The Idea is to get All the SparkPlugs to a Pale, Cream + Coffee Color..... Black is Too Rich...... White is Too Lean....... Water in the Cylinders is a Very New Looking color..... Have you Checked the Timing ???? Good Luck....

affa · Oct 28, 2003

Re: Hard to start after carb rebuild

Hi I did all the tuning as the manual said, the float had to be adjusted 10mm higher then what it was before. The colors of my spark are black. But when I had one out to check the spark it was no spark, and when it came a spark, it kind of moved around the spark, no straight blue spark, but a yellow week spark. I found some water in the cylinders when I moved the spark and run the engine, can this be because of that the engine wont start? When I finally get it started it runs fine, and I can give full gas from 600 rpm and it comes fine all the way. Affa

loadnet · Oct 28, 2003

Re: Hard to start after carb rebuild

affa, You said....

But when I had one out to check the spark it was no spark, and when it came a spark, it kind of moved around the spark, no straight blue spark, but a yellow week spark.

Sounds like you have an electrical problem causing weak spark at start up. - You should have full 12 volts at the coil when you are starting the engine. Try these quicky tests... - Attach a jumper wire from battery positive to coil positive and attempt to start the engine. (You really should change the spark plugs before you do this test ), because they are probably junk by now from trying to start the engine with weak spark. *Engine starts ok? with 12 volt jumper connected? Your carb, distributer, coil, plug wires are all fine - Trace the wires feeding your coil in the key 'start' position. Something along there will be junk or grounding out on route to the coil. *No start? - with 12 volt jumper wire connected? - Distributer internal parts or distributer itself may need replacement. - Spark may be grounding out inside distributer. - Bad coil, or coil wire. - Dirty, worn or cracked distributer cap. One test you can try to see if the distributer is grounding out.. - Remove the distributer cap. - Attach test light ground to distributer housing. - Turn ignition key switch to (RUN) position. - Use a screw driver to Open and Shut the points causing them to spark while at the same time , you stab the inside housing of the distributer with the test light probe. *Test light does not light up or flicker? - Head for the high voltage coil wire and/or coil. *Test light - lights up or flickers? The internal parts of the distributer or distributer itself may be bad/grounding out internaly. Once you are done solving the starting problem you'll need to focus on the water build up situation in your cylinders ?? Can't let that go.. Hope this helps you out.

affa · Oct 29, 2003

Re: Hard to start after carb rebuild

Yes, thanks a lot captain HooknFinger! You were right, there was not enough voltage on the coil, I found the main electrical coupling to the engine filled with water, strange that should happen now, but anyway my carb and electrician are tuned up, so I got to focus on the water coming in to my cylinders. Iheard a kind of sucking noise from the engine when I tuned it very little to set the point gap, and I have read that it can suck water in to the cylinders, but I am not sure and would really like to hear what you have to say about it? Thanks a lot again for all answers! Regards Affa

affa · Oct 29, 2003

Re: Hard to start after carb rebuild

Hi again I forgot to tell that when Ive being trying to start the engine with my different problems Ive had a muff on the outdrive, and was thinking if the water pressure there could have anything to do with it, or would it stop in the impeller if that one is OK?

loadnet · Oct 29, 2003

Re: Hard to start after carb rebuild

Well Affa, I'm happy to hear you located the electrical problem - that's great guy! Water Issues: If the engine has not been overheating then I think you can safely rule out the water pump contributing to your water issues. Suction Noise? Weird eh? Check the water inlet hose behind your engine where it comes in (connects to) from the gimbal housing and see if it has 1 or 2 broken hose clamps on it. Look for pin holes in the hose itself. That may be causing you to hear a sucking/water type noise. Check all of your hose connections. Don't just look at the clamps because many times they look ok. Ya gotta put a screw driver on every single one and try to tighten em up a bit. If they're junk, you'll find out real quick cuz they'll just strip or snap on you. As far as water in your cylinders? You could have a - blown headgasket/s - cracked head/s - cracked riser - bad riser to manifold gasket - or cracked manifold/s - yoh? board techs? please jump in if I missed something in this post. CHF You'll have to check each item independently or do a pressure test on the manifolds to make sure they're holding pressure. Take the boat to a marine dealership and have em pressure test them if you are not able to do so at the house. Water in Cylinders...which one? To Start Off.. - Do a compression test and see whatcha get on each cylinder. Write down the max compression per/cylinder. - Look closely at the plugs as you take em out. The one that is the CLEANEST looking is usually the one getting water in that cylinder. Affa, seriously.. - Don't run the boat if you really feel you are getting water in the cylinders. That issue has to located and fixed for sure ok?

affa · Oct 30, 2003

Re: Hard to start after carb rebuild

Hi again CHF I forgot to tell that Ive just changed the manifold to riser gasket, the old one was bad, I used loctite sealant on the new I put in. Regards Affa

loadnet · Oct 30, 2003

Re: Hard to start after carb rebuild

I understand but you still need to do more testing.. What was it you did to determine you had water in the cylinders?

affa · Oct 30, 2003

Re: Hard to start after carb rebuild

I saw the water in the sylinders when I had the sparks out, snd turn the engine in cause there where to much gas in the cylinders, then it flushed out the spark holes. Ive posted this in a new topic since this is about other stuff then my carb rebuild. Thanks again! Regards Affa

affa · Nov 3, 2003

Re: Hard to start after carb rebuild

Hi Again! Ive now done a compression test, and it was between 125 - 150 lbn on each cylinder. Ive also removed the manifold and done a test with filling it with gasoline an it looked allright, I found the bolts a little loose when I removed it, and I saw some water between the gasket and cylinder head. The manifold gasket was not good, and I wonder about the cylinder head gasket? I think I will replace the manifold as it is getting rusty, any suggestion where to buy it? Regards Affa

merc 140 pontoon · Nov 4, 2003

Re: Hard to start after carb rebuild

Hello affa - I, too, am having fun (!%&#@*!) troubleshooting a 140. Two points: 1. I really recommend that you go to Sears and buy a vacuum gauge. I think it cost me 20 bucks. It attaches to the manifold behind the carburetor. There is a 1/4" NPT plug there. I had to go to an auto parts store to find the right tower fitting and rubber vacuum cap, but now I'm set up to check the vacuum whenever I want (and I'm still fighting low vacuum and card idle mixture screw issues). Anyway, it's much more accurate to set the idle mixture screws with a vacuum gauge. 2. Did you use a good gasket sealer on the gasket between the base of the carb and the manifold? I had a "sucking sound", too. I used a short piece of plastic tubing, one end to my ear, one end around the manifold and carb, to find two vacuum leaks. (Be careful near the pulleys and belt!) My leaks were at the base of the carb, in front and in back. Did your new carb base gasket look like this?

My old one did. It doesn't fit the manifold casting correctly--there are gaps where the arrows show. Then if the inside gasket parts aren't sealed well, you get a vacuum leak. I switched to a gasket with no cutouts in it, and used a thin layer of Permatex Ultra Black on both sides. This got rid of my vacuum leaks, but I'm still having problems. Anyway, you might want to read this: http://www.boated.com/topic.asp?TOPIC_ID=47078 I've gotten a lot of help from that forum and from this one. Finally, like Capn HnF says, you do NOT want to run that engine if you really think you're getting water in the cylinders. Not unless you have a drawer full of money you weren't planning to use for something else... Good luck with it. Steve

affa · Nov 4, 2003

Re: Hard to start after carb rebuild

Hi and thanks merc 140 pontoon! My gasket where with no cutouts in it, but I didnt use any sealant. A good idea but the vacuum gauge, I found the idle mixture a little hard to adjust; what are looking for in gauge, highest level when you adjust? Im working with my water in cylinders, and have manifold, carb, cylinder head of to replace gaskets, do you know if I should check for something specially? I was thinking of testing the head with filling gasoline in the water passage to see if there is any leak. Thanks Affa

merc 140 pontoon · Nov 5, 2003

Re: Hard to start after carb rebuild

Hi affa - First you check the timing, then you set the idle speed screw, then you adjust the idle mixture screw(s) to get the highest, steadiest manifold pressure at idle, then you re-adjust the idle speed screw if necessary. Also, make sure the choke is working properly. I like these two webpages for a description of troubleshooting with a vacuum gauge: http://users.bigpond.net.au/ergoff/vac1.htm I don't think I'd be filling large cavities with gasoline. Sounds dangerous to me. I think you should use some gasket sealer on the carb base gasket. I used to use Perfect Seal, but George over at BoatFix.com has convinced me to use Permatex Ultra Black on that gasket. Steve

merc 140 pontoon · Nov 5, 2003

Re: Hard to start after carb rebuild

affa - I also suggest you read the post I listed above, http://www.boated.com/topic.asp?TOPIC_ID=47078 , for a discussion on applying the gasket sealer. George said "It needs to cure a little, like 30 seconds, then put it together and don't tighten the nuts so that both mating surfaces can bed in. Let it sit for like 30 minutes then tighten." You don't want to tighten it too soon or use too much, and end up squeezing the sealant into the intake. Steve

Hard to start after carb rebuild

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