70 HP Evinrude seems to lack a lot of power

[Splaker]

Hi folks,

I recently had my 1982 Evinrude serviced. They did carb work and head gasket replacement. It ran EXCELLENT the first 2 or 3 outings.. all day long. Then this past weekend it stopped working so well! I just bought the boat package a few weeks ago, and the previous owner did admit the engine needed a tuning up. He also complained about a "lack of power" so now I am concerned that the marine mechanic did not address all the issues with the motor. I called the mechanic today and he said it could possibly be related to the power pack needing replacement? Or, perhaps the fuel line is shot? Maybe water got into the plugs? He said try to squeeze the bulb while the motor is running.

It did start without any problems and did not stall.. it did run.. BUT, it could not get up to plane. It seems that it is not firing on all cylinders. Very little power.

Any ideas before I have to take it back to drop another $500?

Thanks!

p.s. I even put STABIL and fresh premium gas in both tanks.

 

[DFozzard]

Re: 70 HP Evinrude seems to lack a lot of power

Hello I have had the same problem. Go drop er back the water and take er out and choke at wide open throttle and see if the power comes back. If so it is fuel related. Also have you changed all fuel lines from tank to carbs? If they are older then 2 years old you need to replace them. Also try taking the fuel line off after the pump and crank it over to see if she is pumping fuel. Just a few things to try. I am not a pro at this but I have been down this road with my 75 hp evinrude.

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

Thanks! I will try! The fuel line is old - at least 4 years old and it's a generic type.. the cheapo one you get at a box store like WalMart.


I will try pulling the choke out too at full throttle.. what should I expect to happen?

thanks

 

[DFozzard]

Re: 70 HP Evinrude seems to lack a lot of power

on your evinrude do you have a push to choke key or manual choke? at wide open throttle you should expect it to plane right up and have power when you choke it at wide open throttle. But like I said I am not a pro jsut a fellow boater trying to help out another boater. here is link to my tread in the forums. http://forums.iboats.com/search.php?searchid=7190313 feel free to read it as I have had a lot of probs with my evinrude but I am gettin er fixed and doing it all myself.

 

[jtexas]

Re: 70 HP Evinrude seems to lack a lot of power

Splaker, you are a long ways from concluding that you have a faulty powerpack. No need to make any wild guesses or blindly throw money and parts at it hoping it'll straighten up. Instead do some basic troubleshooting then just fix what's broke.

Here's what to do before going back to the lake:

First thing, compression test. If your last mechanic was any good, he'll have done it and written your compression results on your bill of work. If it's not on there, call and ask 'im. That way, you'll have baseline numbers to see if there's been any changes. If he didn't do it, cut 'im loose, he's just a parts changer masquerading as a mechanic.

Second, spark test.

You can find directions on these procedures in the "Engine FAQ" section of iboats.

Make sure you are using fresh fuel, the tank is free from water and debris, and the tank vent is open and clear. And the fuel line is holding pressure.

While doing your testing, make a note of the appearance of the spark plugs, especially if one looks different from the others (wet or dry, darker or lighter, carbon-fouled, etc.). They should be Champion QL77JC4 gapped at .030, in good condition.

Go ahead and order your factory service manual. Relax, you never have to put your motor in the shop again.

 

[Challenger84]

Re: 70 HP Evinrude seems to lack a lot of power

I just had the same problem.
I have a 16' open bow with a 83' 70hp Johnson
The problem was that my fuel filter was clogged up and not enough fuel getting to the first cylinder.
Do a cylinder balance test to see which cylinder is the faulty one.
Then work from there.
Like some have said make sure you do a compression check and spark check.
Good luck on your motor!
I'm sure these guys on here will help you through it.

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

Splaker, you are a long ways from concluding that you have a faulty powerpack. No need to make any wild guesses or blindly throw money and parts at it hoping it'll straighten up. Instead do some basic troubleshooting then just fix what's broke.

Here's what to do before going back to the lake:

First thing, compression test. If your last mechanic was any good, he'll have done it and written your compression results on your bill of work. If it's not on there, call and ask 'im. That way, you'll have baseline numbers to see if there's been any changes. If he didn't do it, cut 'im loose, he's just a parts changer masquerading as a mechanic.

Second, spark test.

You can find directions on these procedures in the "Engine FAQ" section of iboats.

Make sure you are using fresh fuel, the tank is free from water and debris, and the tank vent is open and clear. And the fuel line is holding pressure.

While doing your testing, make a note of the appearance of the spark plugs, especially if one looks different from the others (wet or dry, darker or lighter, carbon-fouled, etc.). They should be Champion QL77JC4 gapped at .030, in good condition.

Go ahead and order your factory service manual. Relax, you never have to put your motor in the shop again.

Mechanic did a compression test. Report says it its good - I believe 140ish?

The spark test I did not do... how much do one of those gadgets cost? I don't want to be spending a lot of money... how often will I do a spark test?
What should I look for with the plugs? I checked them.. they smell like fuel and they are a bit darkish, but I don't know what a "bad" plug looks like.

I have metal tanks - is there a vent opening on those things? I couldn't find one...

Fuel us good - use premium and added STABIL ethanol treatment..
Thanks!

 

[jtexas]

Re: 70 HP Evinrude seems to lack a lot of power

Compression results will be 3 numbers, one for each cylinder. 140 is excellent, I would have expected closer to 120, but the important thing is consistency across all cylinders.

Inline spark tester, about $5 at autozone. You'll want to do a spark test whenever you have a performance problem without an obvious cause.

Compression test and spark test are quick & easy to do, so those are always the first steps in troubleshooting.

Google "reading spark plugs". A light coating of oil on the plugs after idling is good.

Yes your tank needs to be vented, or else the fuel pump has to pull against a vacuum, which it isn't designed to do. Portable tanks, the vent is usually a thumbscrew in the lid. Built-in tanks are required to have a vent hose with an opening on the outside of the hull.

Higher octane fuel isn't more powerful, it's less volatile, to prevent preignition in engines with high compression ratios. Your motor was designed for 87-octane gasoline -- anything more is just a waste of money. The stabil is a good idea, though.

 

[outlaw241]

Re: 70 HP Evinrude seems to lack a lot of power

while you are at auto zone i would rent a compression tester for free [deposit required so you will return it] just so you know for sure instead of 140 ish.

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

while you are at auto zone i would rent a compression tester for free [deposit required so you will return it] just so you know for sure instead of 140 ish.

I am in Canada. We have Napa Auo PArts. I am assuming they sell them?

Compression tester for rental is something I will have to look into.

Thanks folks! You've been very helpful

 

[Challenger84]

Re: 70 HP Evinrude seems to lack a lot of power

Make sure you do a compression test for your self to comfirm your mechanics numbers..
Have you tried the cylinder balance test yet? To find the bad cylinder?

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

Make sure you do a compression test for your self to comfirm your mechanics numbers..
Have you tried the cylinder balance test yet? To find the bad cylinder?

Cylinder balance test? Guys, keep in mind I am VERY inexperienced when it come to this stuff - as in no experience!

That is why I am here and why I rely on a mechanic to get the job done. But I'd like to wean myself off of them.

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

Compression results will be 3 numbers, one for each cylinder. 140 is excellent, I would have expected closer to 120, but the important thing is consistency across all cylinders.

Inline spark tester, about $5 at autozone. You'll want to do a spark test whenever you have a performance problem without an obvious cause.

Compression test and spark test are quick & easy to do, so those are always the first steps in troubleshooting.

Google "reading spark plugs". A light coating of oil on the plugs after idling is good.

Yes your tank needs to be vented, or else the fuel pump has to pull against a vacuum, which it isn't designed to do. Portable tanks, the vent is usually a thumbscrew in the lid. Built-in tanks are required to have a vent hose with an opening on the outside of the hull.

Higher octane fuel isn't more powerful, it's less volatile, to prevent preignition in engines with high compression ratios. Your motor was designed for 87-octane gasoline -- anything more is just a waste of money. The stabil is a good idea, though.

There are no "thumb screws" on the cap.

 

[Challenger84]

Re: 70 HP Evinrude seems to lack a lot of power

cylinder Balance test=
1. Start OB on muffs
2.pull the spark wires off the p;ugs one at a time and see if the engine chokes, If it doesn't do anything when you remove the wires then that's the cylinder that is bad.
If the Engine chokes a bit then that cylinder is good.

Compression tester is under $50.
Mechanic testing it for you 1 time about $50
Your choice..

 

[jtexas]

Re: 70 HP Evinrude seems to lack a lot of power

If there's a vent on your tank it shouldn't be too hard to find.... I don't know anybody that makes a portable outboard motor gas tank without a vent, but I guess there must be somebody out there. If there's no vent on the tank then the tank's no good.

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

So if I discover that there's no spark in one of the cylinders, what are my options?

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

Compression results will be 3 numbers, one for each cylinder. 140 is excellent, I would have expected closer to 120, but the important thing is consistency across all cylinders.

Inline spark tester, about $5 at autozone. You'll want to do a spark test whenever you have a performance problem without an obvious cause.

Compression test and spark test are quick & easy to do, so those are always the first steps in troubleshooting.

Google "reading spark plugs". A light coating of oil on the plugs after idling is good.

Yes your tank needs to be vented, or else the fuel pump has to pull against a vacuum, which it isn't designed to do. Portable tanks, the vent is usually a thumbscrew in the lid. Built-in tanks are required to have a vent hose with an opening on the outside of the hull.

Higher octane fuel isn't more powerful, it's less volatile, to prevent preignition in engines with high compression ratios. Your motor was designed for 87-octane gasoline -- anything more is just a waste of money. The stabil is a good idea, though.

As per consistency, I just looked over the mechanic's report once again and discovered his reference to the compression test. According to his written report, spark was present in all 3 cylinders and the compression was as follows: 145/145/125. So the last one was lower. Is this acceptable or should it be in line with the other two? They also found water present in cylinder #3 at the time of the diagnosis.

Thoughts?

 

[patrick4266]

Re: 70 HP Evinrude seems to lack a lot of power

Just a wild guess but you could have a leaky head gasket causing the lower pressure and the water leak.

 

[Splaker]

Re: 70 HP Evinrude seems to lack a lot of power

Just a wild guess but you could have a leaky head gasket causing the lower pressure and the water leak.

They worked on the gaskets.. they were replaced.


Just bought a compression tester. I bought it in the automotive section of a box store. It's labelled for cars, but I am assuming it'll work for my engine. Yes/no?

 

[Challenger84]

Re: 70 HP Evinrude seems to lack a lot of power

The compression should only have only a 10% Max in difference.
Yes the car compression tester would work for your OB.

If they worked on your gasket and it didn't help then I don't know what to tell you ....
You have a bad motor..Sorry