1987 Evinrude 70hp, can't hold idle

[Tim Kane]

I have a Evinrude 70 hp motor E70ELCUR, and it stalls after a couple seconds when first shifting into forward, or reverse. This is my first season with this boat so it's new to me and when I bought it the guy told me it did not like to idle. The gas is fresh. Filters are new. A quick increase of throttle keeps it going and it will run all day an any speed except for idle. I tried messing with the idle adjust screw but it seems like this was not the answer. Made for shifting at too high of a speed. So if shift into forward and give it more throttle right away, it's fine but as you can imagine, this makes docking very difficult if not dangerous, with constant stalling starting. I removed all three carbs and cleaned them. Inspected them for any cracks or anything that was different, they all looked very clean. I cleaned them again and re-installed. No change. I made a very small butterfly valve position adjustment on the top carb (on the linkage that connects all three) and that increased idle speed a bit but did not cure the stalling issue. I don't know what else I can adjust. Can anyone help me out with this problem? I appreciate any help. I have spent hours on this and I am about to give up.

 

[racerone]

Most carburetor " problems " turn out to be something else.--Start with a compression test on it.------One of those motors in good condition will idle all day long !

 

[Tim Kane]

raceone: I don;t have a tool to check this. Maybe I could rent one or buy if not too much. I have to ask, would running fine at all other speeds indicate the compression was ok?

 

[racerone]

You should do a proper test for compression !-----------Proper trouble shooting will help solve the issue with the motor.------Guessing and assuming does NOT work on these motors.

 

[eavega]

raceone: I don;t have a tool to check this. Maybe I could rent one or buy if not too much.

Most auto shops around here (O'Riely's, Autozone, Advance Auto Parts) will "loan" you a compression tester under their tool loaner program. Those programs work by "selling" you the tool (you pay for it in full) and you return it in working condition within a certain number of days. I do it for tools that I would only use occasionally like an inch-pound torque wrench or a bearing puller. A compression test, however, is usually troubleshooting - step one. I would recommend finding your nearest Harbor Freight or Northern Tool and plunking down the $25-$30 and buying your own. As I said, compression test should be your first test when troubleshooting an internal combustion engine not running right (be it boat motor, lawn and yard equipment, automobile etc)

-E

 

[Tim Kane]

Most auto shops around here (O'Riely's, Autozone, Advance Auto Parts) will "loan" you a compression tester under their tool loaner program. Those programs work by "selling" you the tool (you pay for it in full) and you return it in working condition within a certain number of days. I do it for tools that I would only use occasionally like an inch-pound torque wrench or a bearing puller. A compression test, however, is usually troubleshooting - step one. I would recommend finding your nearest Harbor Freight or Northern Tool and plunking down the $25-$30 and buying your own. As I said, compression test should be your first test when troubleshooting an internal combustion engine not running right (be it boat motor, lawn and yard equipment, automobile etc)

-E

OK, I did the compression test. Rented from AutoZone. The results show all cylinders are about the same at about 100. Didn't seem to matter if the engine was warm or cold, the results were essentially the same. I am trying to find out what the compression spec is. I don't know at this time.

The poor idle is still an issue. Ran the boat last night and it ran great for about an hour at varied throttle positions. Wide open to just 4 knots all fine, then when I am trying to dock it at idle, it keeps stalling.

 

[fireman57]

I understand that technically you should check compression to make sure that you are not chasing a problem on a bad engine. That being said when it runs fine at WFO and won't idle it is 92% of the time (I made this stat up) it is in the carbs. Take them apart and make sure all jets, especially the low speed jet is clean. If you need to see a diagram of them go to ishopmarine.com and you can pull it up. Carbs are not that difficult. Just take you time. I would almost guarantee that a good cleaning fixes your problem.

 

[flyingscott]

haw fast does it idle in neutral maybe someone before you turned the idle down

 

[Tim Kane]

I understand that technically you should check compression to make sure that you are not chasing a problem on a bad engine. That being said when it runs fine at WFO and won't idle it is 92% of the time (I made this stat up) it is in the carbs. Take them apart and make sure all jets, especially the low speed jet is clean. If you need to see a diagram of them go to ishopmarine.com and you can pull it up. Carbs are not that difficult. Just take you time. I would almost guarantee that a good cleaning fixes your problem.

Carbs were removed and cleaned thoroughly. (See first post). played with the idle adjust scre. When I got it to idle without stalling, it was too fast in neutral. Shifting was too hard.

 

[AlTn]

try decarbing the motor...look under the sticky ...Top Secret Files < highlighted in yellow at the beginning of the Forum > for the procedure

 

[flyingscott]

Get the manual and do a linc and sync make sure everything is is working correctly

 

[Tim Kane]

try decarbing the motor...look under the sticky ...Top Secret Files < highlighted in yellow at the beginning of the Forum > for the procedure

Look under the sticky? Sorry but I don't know what that is.

I don't think decarbing is going to help. It runs great at all speeds other than idle. Plenty of power at both low and top end. If I had a significant carbon build up I would be losing power.

I am convinced it's a carb adjust problem. The high and low speed jets are fixed so there has to be some other adjustment. I found an aftermarket manual for it and there is something in it I would like to try and see if it helps. It;s a procedure for adjusting the butterfly valve position for idle. The manual says they should be shut on all cylinders. I don't think that is the case on this motor, maybe get to try that tonight if it stops raining.

 

[bouttime007]

The sticky thread (pinned with a stick pin to remain in place) is the 1st thread on top of this board.

You can read it but not post in the thread.

 

[Chinewalker]

A quick and easy thing to check - make sure the thermostat is present and working. I had a 1990 version and it would not idle at all. I discovered that a previous owner had removed the thermostat thinking that would somehow fix a cooling issue, I guess. I installed it and the motor ran perfectly. It was simply never getting up to operating temps and always running cold.

 

[jakedaawg]

after the compression test it is time to do a spark check. This is done with an open air gap spark checker set to 7/16". No other method of checking spark is suitable. A weak spark on one cylinder will give the problem you are having.

 

[Tim Kane]

I still have not found any information on the compression results. Can anyone tell me if 100 psi is a good number for compression on a 1987 Evinrude 70?

 

[Bosunsmate]

I still have not found any information on the compression results. Can anyone tell me if 100 psi is a good number for compression on a 1987 Evinrude 70?

Not me but did you read the post #14 about thermostat?

 

[flyingscott]

Do not set your idle with the carbs it doesn't work. your idle speed is controlled by the timing advance not the carbs that cam needs to open the carbs at a specific point you need to make sure that is happening. when you put the motor in gear you are loading the motor up that timing being off will will cause it to die. Do the link and sync and get a different compression tester I would expect a healthy 70 to be 120+

 

[racerone]

Just did a quick diagnostic check on a 1990 model 70 hp.----------centre piston was a little low and finally came up to 110 others were 120.------Took the head off and showed owner the scored centre cylinder.--------Owner saw it all and said --" thank you very much , and could you please repair this motor "-----------Nothing to this stuff !!!

 

[Tim Kane]

Spark is fine.