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2007 bayliner 185 w mercruiser 43 carb model TIMING ISSUES

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bushwhacker

Member
"Alright. I didn't know to

"Alright. I didn't know to drain my block last winter, spent over 8,000 so far. Got a new motor in, remanufactored mercruiser marine engine. I watched the guys at a shop in Havasu, AZ put it in. Came back home to Pinedale, WY(which is 7,500ft. elevation) and went to run it on the lake. They set the timing there in havasu as well. it idled fine once they got it set. So We got it out on the water, got engine temps up to 160F. Got up to 1800RPM and backfires constantly. Tried advancing the timing and only got worse. Tried retarding timing, killed motor. So today, I took the carb off, I needed to change the jets anyways. It had 1.55mm in and its running way rich, so I am goin got try 1.50mm and if'n thats still too much, go to 1.45mm. Carb wasn't gunked up like I had hoped, cause that would be easier to deal with. But I pulled the carb and am cleaning it. pulled the plugs, and they're barely black, not sooted up. Just trying to figure out what to do next, cause I treated my fuel last year before storage with Stabil, but could that cause this exstensive backfiring? Some other people think the distributer is cracked or rotor plate is cracked, My engine came from US Engines in Kent, Washington. Is there a possiblity that the timing chain is off a tooth with the crankshaft, cause those guys at US engines seem to know their crap, so i doubt it. The engine came long block assembled. So Im not sure where to go from here, any ideas? Thanks alot guys."
 
"also, we checked the firing o

"also, we checked the firing order 165432, and its right on the distrib cap. so thats one more elimination. Plugs are close to gap. within 3 thousands. Im changing the fuel/seporater, drained old gas. it was sitting for about a year with stabil treatment. should have new gasket kit for carb in a couple of days, so I can get some new fuel and put in the 1.50mm jets, bolt cleaned out carb( even though it wasn't really dirty) back on.
Now should I set the timing all over again, hook up the purpl/white wire to grnd. turn on key. bump ignition key till TDC. set back 10' from TDC. tighten bolt on distrib. start it up and adjust with timing light or is that all jacked up?"
 
"another thing, the gas i drai

"another thing, the gas i drained out of the tank tonight, wasn't like varnish smell, but didnt have the punchy smell that new gas has. it also, had a darker green tint to it. the bowl of the carb, didnt have really any trash at all in it, just a slight layer of residue, barely anything all at the bottom. little bit of builtup residue on the float spring and retainer spring. Other than that it was a pretty clean carb for sitting a year. this really has me stumped."
 
"Rod or Guy... you guys got an

"Rod or Guy... you guys got any idea what Im dealing with here. Your professional opinion means worlds to me, much thanks. j.d."
 
"JD--
I'm no pro(fo

"JD--
I'm no pro(for sure) but it sounds to me like you may have your cause in the old gas and the carb jetting/mixture. I don't think you can reasonably do anything until you get all the old gas out, at a bare minimum it sounds like it's stale, if not worse. I ran across a lawn tractor once that was being really naughty and it was the same situation--we drained all gas(which had stabil in it) put in new and she ran like a top. I have heard that stabil is not the best fuel preservative out there in more than one forum before. Hope you get it

--chris"
 
"JD Bush:

If the carb was o

"JD Bush:

If the carb was on the previous engine and it ran fine before the new one was installed, why rejet the carb? Backfiring has a number of causes; out of time, burned valve (not your case), lean mixture, crossfire from bad wires or carbon tracked dist. cap, vacuum leak, etc.

Set the timing per specs., clean and gap plugs, CLOSELY inspect the dist. cap, rotor and wires; replace as needed. Check plug wire routing so they don't cross.

Dump a can of SEA FOAM in the tank w/10 gals. of fuel. Get it running. If it still backfires check for vacuum leaks around the carb base and intake manifold gaskets. You can spray carb cleaner along the gaskets; if the RPMs go up or the engines starts to choke up, that is the leak.
A small vacuum leak will increase RPMs while a large leak can choke the engine. BTW, I am only a backyard mechanic. Good luck."
 
"first, carb jetting can resem

"first, carb jetting can resemble timing issues and cause back firing.

second, set your base timing to spec. replace cap and rotor, then jet carb if needed.

Third, a leak down test will tell you if and what intake valves are leaking. they may have gotten the lash wrong or worse. sounds like you may have a vacume leak. check by spraying carb or brake cleaner along intake and carb base
and listen for idle changes would be a good start."
 
JD;
The lads have you covered

JD;
The lads have you covered with the above suggestions.
I have to think you NEED to FIRST completely drain all the old gas and crap out of the tank and start with fresh to remove that unknown. Then you at least know what you are trying to burn.

Rod
 
"thanks guys, I appreciate it.

"thanks guys, I appreciate it. tonight I was looking again, and noticed a sensor that has no harness pluged into it, by the crankshaft pulley. This is obviously a crankshaft sensor, and i think this could be the problem. Because guys, this thing was out way bad, no adavancing of timing would help or retardation of timing. I checked the firing order again tonight and its right. I inspected the rotor and distributer cap, and it look brand friggin new, no small cracks or anything to raise suspision. Right now I am going to go inspect the screen that is inside the inlet to the carb. If its dirty then I will believe its fuel problem, but right now I dont think fuel is the culprit. I did drain the tank, I got a new fuel/water seporator coming, plugs are gaped to .045, wires aren't crossed. The distributer does not need to be fliped 180'. We checked the position the the distributer when number one piston is TDC. The motor is right. I really think it is the cam shaft sensor, or maybe fuel."
 
"lash meaning, valve lash. if

"lash meaning, valve lash. if your valve lash is to tight (not enough slack) the valve or valves will not fully close. hydraulic lifter lash setting is easy to perform. A tight or binding
valve guide could also hang a valve also.
start with the basics.
if you don't have leak down tester, you can use low pressure shop air. bring the cyl. being tested to tdc and apply low air pressure. (DONT leave wrench on crank as engine may turn once air is applied) also leave all other spark plugs in to aid in holding engine from turning)
then listen for air coming up through intake,
exhaust and crank case. if air is heard in intake
the intake valve is not closed or is leaking.
if heard in exhaust, an exhuast valve is. It is normal to get some air through the crank case as no piston rings ever seal totally.
a compression test would also be a good start
as this would be an indicator of problems also.

? If it's carbed, why would you have a crank sensor?"
 
"thanks Kurt S. I get the valv

"thanks Kurt S. I get the valve lash thing now, but have not gone into check it out yet. Im almost certain this is a fuel delivery thing. I cleaned out the cyphon valve from tank to fuel/water seporator and it was completely full of trash, like the hole was totally plugged up. And the motor has been idleing fine with this trash blocking a large quantiy of fuel from coming through. but everytime i try to run the motor up, at 1600-1800 rpms, it hesitates and backfires, wont go anymore higher on rpms either. Its got to be fuel starvation. Runing lean, because not enough friggin fuel I guess. I am doing a fuel pressure check on the fuel system tomorrow. I took the entire fuel system apart tonight to check for trash, but found none anywhere. From tank to carb. So once again, I dont know where to look. If it is a vavle lash issue, where do I even start with lossening that? Can I just take the valve cover off and work on it? I have no clue. Thanks again, J.D>"
 
""I have no clue" you

""I have no clue" you are going to Fook your new engine fool, take it to a profesional"
 
"Mr. Peter Lang- I am not goin

"Mr. Peter Lang- I am not going to "fook" my new engine. I have taken it to professionals. I have spent more money on labor than anything so far. The only thing I dont kow how to do myself is adjusting the valve lash, and I dont mess with things I dont understand. So today I am checking fuel pressure, its supposed to be about 5lbs. at idle. Peter- Have you ever been so frustrated because you've tried just about everything, and so has the mechanics that put your new motor together, that you end up expressing yourself with a phrase like, " I have no clue.....what to do." ? Once again, I know when to stop, I know what is safe for me to work on, if you think im incapable of this, then you should find another board to post in-genius replys like, " take it to a professional." deek-cheese."
 
"Easy boys; there is no need t

"Easy boys; there is no need to get silly on us.
This is a nice well run professional forum, and we'd like to keep it that way.

JD; you don't need a CPS with a carbed engine, so don't worry about that plug. It is there likely because the base block package is intended to be used either for carbed or MPI applications.
I would not mess with valve lash or any other issues you might dream up until you assure that fuel delivery is adequate.

Like we said earlier, you need to completely clean the old crap out of your tank and start clean there. Then I would clean or flush out all lines, then change all filters. Don't forget the small porous filter at the carb inlet fitting, if so equipped. It does not take much to plug this little guy. You can clean and reuse it.

Then you can T a pressure gauge into your fuel line at the carb and make sure you have 5 psig or so at all load conditions. This will assure adequate clean fuel delivery. If that does not solve your problem, then its time to look elsewhere.

Rod"
 
"dear Rod- so far I have: Suck

"dear Rod- so far I have: Sucked out tank, taken fuel system apart from tank to carb, changed fuel/water seperator, cleaned screen(nothing in it) inside carb inlet. Checked for vacuume leaks around carb and intake manifold gasket, we checked fuel pressure today and was at 7lbs. We checked firing order again, replaced plugs, set timing again, swapped ignition module with a friends boat same as mine, nothing changed. Next we are going to check compression at each cylinder. Also, spark to every plug is there.Idles fine, but its like the ignition module is searching for optimum spark by slighty advancing or retarding., by the way it sound at like 1,500rpm's. At 1800-1900rpms its backfiring through the carb. Its not running lean, we poured small amount of gas into the carb, and the motor did not pick up. I bought the motor from US Engines Only in Kent, Washington, Came to the shop that did the swap in Havasu,AZ. SPARK< FUEL<AIR<TIMING have all been searched out thouroghly on the motor and we cannot seem to question anything else besides valve train, etc..."
 
"the problem with that Guy, is

"the problem with that Guy, is I can never get the Owner of the shop to answer his phone, cell or shop. Can I explain to you the way the rockers look, the tension or lash as they call it. When the #1 pistion is at TDC both intake and exhaust valves are closed, rockers are flat-even-have play side to side, #3 and #5 pistons are one valve closed and one valve open. Now on the other side, the left bank, pistons 2,4,6- all valves appear to be closed, because all rocker arms are flat and springs are unloaded. This seemed to be quite odd to me, is it a sign of anything? Thanks man, J.D."
 
"Did you use original distribu

"Did you use original distributor, or was that replaced with the engine assembly? I have had distributors with worn bearings that allow the shaft to track in a very slightly egg-shaped pattern that produced conditions similar to what you describe. Running long enough with backfiring can burn valves, further complicating situation. If you are using older distributor, I would have an auto-electric tech check it out.

I realize that you have checked the distributor cap for cracks, but have you actually repaced the cap with a new one? Very seldom do I ever see a cap that visually "looks" bad - but it is. And I have had brand new caps that were bad as received - which really drives you crazy when troubleshooting."
 
"Thank you very much David for

"Thank you very much David for you response so soon. The distributer is the original. I have ordered a new distributer assembly last week from CFM-tech and it should be here tomorrow,so far everybody that i know says there is nothing wrong with the distributer, and it is making spark. But yeah, I can't figure out why This problem is so hard to figure out. I am also not runnning the motor anymore, maybe 2hrs. so far in testing. But did you read what I typed earlier about the position of pistons 2,4,6 when #1 is at TDC? It just seemed weired to me. Dont know if there anything to it. But In my mind the motor's valve train should follow the firing order from TDC. And the way it looks it that at TDC #1. Valves for 2,4,6 are all unloaded, wiggley, whatever you want to call it.
Thanks man , J.D."
 
"NopeNope, its not the valve t

"NopeNope, its not the valve train, I called a guy and it all correct. I dont thing the lash is wrong either. I do think the only thing to try is the distributer when its comes it tommorow. And if that isnt it....wow. Maybe' its the steering colume fluid resevoir sensor adjustment screw housing filter, right below the switch bracket."
 
"JD:

I'm sorry man but

"JD:

I'm sorry man but I'm not well versed on internal engine adjustments. All I can say is that valves are set w/a feeler gauge and tightened to a specification. An intake valve on one cylinder can be adjusted at the same time an exhaust valve is on another cylinder based on the firing order.
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"
 
"JD:

Did you substitute a d

"JD:

Did you substitute a different coil yet? Seeing a spark means little more than SOME voltage is getting to the coil. If you don't have an oscilliscope to monitor the spark pattern you are shooting in the dark.

Somebody just solved a similar problem when Rod told him at the beginning to change the coil. It now runs perfect w/a new coil which was the last thing he replaced.
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"
 
"JD;
The valves should defini

"JD;
The valves should definitely follow the standard pattern according to the firing order as you suggest.
You should be able to confirm this by watching the valves move as you slowly rotate the engine CW with a ratchet bar on the damper pulley nut.
If any of them do not actuate, you could have a collapsed lifter.
Actually a compression check should immediately tell you if the valves and other vital parts are behaving according to plan.
Have you done this yet?

Rod"
 
"Rod- no i havent done a compr

"Rod- no i havent done a compression check mainly because its sunday now, napa is closed and I was about to dive into this area last night, but I first want to fully investigate all electrical/ignition possiblities. So just a few minutes ago I check a ground wire that goes from the distributer to the block, because the guys who put my motor back together used a bullet connector and it seemed loose to me, so I re-terminated it myself and just fired up the motor to try it out, it didnt change anything. I already have a new distributer coming, tomorrow, and someone on here suggested that the coil could be going bad/out or something. Yesterday we held the #1 cylinder spark plug to ground and I watched it spark and it seemed fine, but who knows. Is there some way I can use a volt meter to test the coil and know if it is producing the correct amount of voltage? Instead of just yarding off parts and putting new ones on, I would like to try and diagnose this Mercruiser 4.3 L/X Alpha 190 HP w/ 2 brl Mercarb running 1.50mmjets, changed plugs yesterday, they were totally black, rich, sign of plenty of fuel, not burning it all, so it either ignition,timing, or cam gone soft, valve burnt, I dont think the lash it out. So yeah, thanks again guys"
 
"can anyone call me about this

"can anyone call me about this, last night i put in a new distributer and coil, so its not ignition problems, its still backfires. thanks alot 307-390-7244 j.d."
 
JD:

Do the compression test

JD:

Do the compression test dry and again wet with a tbs. of oil in the cylinder. Record readings to compare and see what you get.
 
"yeah Rod, that makes sense. I

"yeah Rod, that makes sense. If I take that lid off, what can I look for the float to be doing, because it idles ok. Thanks again"
 
"Still Cant figure this out gu

"Still Cant figure this out guys...its really starting to chaff my butt. Last night I tried setting the timing again, at a idle of 1200rpm, but its was already at 10' BTDC. So I then took the top cover of carb off, checked for trash, float is not stuck and put my 1.55mm carb jets back in. Took it out side, ran the same, idles fine, then around 1,600rpm hesitation starts and and 2,000rpms backfires through the carb. I really feel that I have investigated the electrical and ignition pretty well on this, Please someone help me. Thanks again, J.D."
 
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