merc 3.0 engine falls flat on face in reverse

[rebelmandziukan]

hi everyone its me again. i have a mercruiser 3.0leter 4cylinder on a alpha 1 gen1 setup. this boat is my project and has never seen water since i have owned it (1 month) its a 1990 cheetah lsc. the engine cuts out in reverse it does good in drive and neutral but when i go to shift it into reverse it starts to raise the rpms and then cuts out like i turned off the ignition any ideas? im stumped!

 

[Fishermark]

Re: merc 3.0 engine falls flat on face in reverse

then cuts out like i turned off the ignition

I'm not sure what you mean by that - you mean simply that it dies? Sounds like the lower shift cable either needs adjusted or replaced. See if the shift interupt switch is moving and staying in the "up" position as you shift.

 

[markvictor]

Re: merc 3.0 engine falls flat on face in reverse

Fishermark hit the nail right on the head....

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

allow me to elaborate. when i shift into reverse the engine dies and smoke comes out of the carburator.where is the shift interupt switch?i will adjust lower cable tomorrow and fill you in. thanks in advance.

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

ok i found out where the shift inturupt is but its too dark outside to work ill post results tomorrow

 

[Fishermark]

Re: merc 3.0 engine falls flat on face in reverse

too dark outside to work

I see you are posting from Orlando - it's not dark yet... but ... admit it... with that cold front that has blown through it IS too cold!!!

 

[Don S]

Re: merc 3.0 engine falls flat on face in reverse

Too COLD? what, It's below 80? <br /><br />Anyway since you have a need to stay warm and in the light, sit at your computer and read up on your engine and drive. Here are the links to the ONLINE manuals for your engine and drive.<br /><br /> Alpha I Service Manual <br /><br /> 3.0L Mercruiser Engine Service Manual

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

oooooo yes! THANKS for the service manual links. and yep ill admit it, its ballshrinking cold down heere or up here depending on where you are lol

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

ok guys the shift inturupt switch is indeed staying in the up position. in other words the switch does not return to the off position when in reverse. it does ingage and return to center when in forward but when shifted to reverse it engages but does not return to to center. can i adjust it or is it bad?

 

[Fishermark]

Re: merc 3.0 engine falls flat on face in reverse

can i adjust it or is it bad?

If you can't adjust it, then it's bad. <br /><br />Okay, that's a little simplistic, but you get the idea. If it is hard to pull, (disconnect it and try it by hand while a helper turns the prop in the appropriate direction), then it is bad.<br /><br />Here's a picture showing adjustment:<br /><br />

<br /><br />Image taken from Mercstuff.com

 

[Fishermark]

Re: merc 3.0 engine falls flat on face in reverse

Here's another set of instructions. I have this on my computer, and I copied it from someone here on Iboats a long time ago. I don't remember who posted it originally, or I would give them the credit. <br /><br /> Adjustment of the cables <br /><br />1. Remove both the shift cable (to leg) and the control cable (from control box) from the shift plate.<br /><br />2. Push in on the end of the shift cable and have someone turn the prop slowly Counter clockwise at the same time. When the prop stops the unit is in Forward gear.<br /><br />3. Adjust the brass barrel on the shift cable until the distance between the center line of the brass barrel and the cable end guide mounting hole is EXACTLY 6 inches. (pre-1974, 5-7/8")<br /><br />4. Re-install the shift cable onto the shift plate. DO NOT change this adjustment again.<br /><br />5. With the control lever at full throttle in forward adjust the brass barrel on the control cable to line up with the guides on the plate. DO NOT install the cable at this point.<br /><br />6. Turn the brass barrel AWAY from the cable end guide 4 turns. Install the cable on the shift plate.<br /><br />7. Move the control lever to the full reverse position, as the helper turns the prop slowly clockwise until it stops.<br /><br />8. Check the shift cutout switch roller position. If is has moved from the center position, adjust the brass barrel on the control cable, one turn at a time (maximum 4 turns) until the roller is in the center position.<br /><br />9. Secure the cables with the nyloc nuts. DO NOT tighten them onto the barrels.<br /><br /> Cutout switch <br /><br />The cutout switch should also be checked. The correct adjustment for the switch is to activate when the switch arm has moved 1/8". Check this with a 1/8" drill and a multimeter. With the key 'OFF' put the multimeter across the switch (points ignitions will have to have the points open for this) and start moving the switch arm. When the meter shows that the switch has closed, check the gap between the switch arm and the actuating lever, it should be 1/8". Bend the arm of the switch to achieve the dimension.

 

[Don S]

Re: merc 3.0 engine falls flat on face in reverse

You don't have an adjustment problem, your cable is bad. It doesn't take much corrosion to slow those cables down, and they get replaced quite often. I do lots of them every year.<br />Go back to that manual and learn what it takes to replace the cable. Make sure the shift shaft in the pivot housing is also free to move and not stiff, install a new cable, adjust BY THE BOOK and you should be set to go.<br />The manual I gave you a link to is what all these other sites refer to. Follow the information in the book step by step and it will work when your done....... Try short cuts and you will have problems.

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

cool thanks a bunchill try this and post the results.

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

so let me get this right. my lower shift cable is bad causing the shift interupt switch to stay in the "out" position thereby killing the engine ..right? I'm just trying to understand the problem.

 

[Fishermark]

Re: merc 3.0 engine falls flat on face in reverse

You have it right. A bad lower shift cable will do exactly what you describe... And DonS is probably right, (imagine that! ), you probably need a new lower shift cable. But before you go out and buy and install a new one, try adjusting the existing one first. If for no other reason to see how to do it with the new one! Who knows? You may get lucky and not need a new one. I have replaced and adjusted my share of them as well - I know that sometimes it is simply out of adjustment. Especially if someone has been messing with it and has gotten it all "out of whack."

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

I went put and bought a new cable but ill have to install it next weekend cause we are having perfect weather this weekend to glass in the new floor which i just got done with the first coat. ill post next weekend on the results of the cable install.

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

ok fellas i replaced the lower shift cable and adjusted it by the book now the shift inturupt switch wont move at all what happened?

 

[rodbolt]

Re: merc 3.0 engine falls flat on face in reverse

if your not in the water its common. the only time the shift interupter will trigger is if the propeller is loaded. it only works if the prop is spinning and in the water and your moving the shifter from an in gear position to an out of gear position.<br /> if the cable is free most of them wont move the inturupter on the trailer. if it does the cable is most likly binding.<br /> if the instructions are followed it works. miss a step or perform one incorrectly and its a mess.<br /> I use a bungee wrapped around the prop to hold the unit in fwd while I am attaching the cable guide and anchor. and dont let anyone talk you into packing the slide pocket on the gimbal hsg with grease. and dont tighten the shift slide set screw with a wrench. but if you read and head the directions it works.<br /> BTW did you carefully inspect the upper shift shaft seal in the gimbal housing exaust area?<br /> if you had water in the shift slide area odds are thats what took the cable out.

 

[rebelmandziukan]

Re: merc 3.0 engine falls flat on face in reverse

cool so i did fix it? fantastic! there was no water in the shift slide area. a great big thanks to everyone who was involved in this post. (rebel stands at attention and snaps a smart marine corps salute) you guy are gold and thanks for putting up with my newby questions.ill have more stuff soon.