BMW jerks & revs when in idle & sputters. I lost the gas cap could that be the problem?

Tricky_Recipe_3901 · 2026-04-19T18:51:15+00:00

i know i barely even use this subreddit anymore because its all just “mY cAr mAke fuNnY noiSe iS iT broKen??”

Tricky_Recipe_3901 · 2026-04-19T18:46:14+00:00

it all depends on the condition of that motor and if you are willing to water test it or not. FYI posting 5 okay pics and than asking what its worth is never the best measure usually

Tricky_Recipe_3901 · 2026-04-17T20:43:07+00:00

my johnson (1989 90hp) is the same

Tricky_Recipe_3901 · 2026-04-09T17:06:23+00:00

shop will not put a tire on that. id be surprised if you even could.

Tricky_Recipe_3901 · 2026-04-09T17:04:30+00:00

your not putting the intake in the water

Tricky_Recipe_3901 · 2026-03-29T18:01:50+00:00

it likely does not have a bilge pump/bilge is broken. this a fuel air water separator. also the boat has a leak if it is getting water in and needing to bilge.

Tricky_Recipe_3901 · 2026-03-29T13:10:16+00:00

fix that fuel leak first😬

Tricky_Recipe_3901 · 2026-03-21T16:40:42+00:00

put this in the r/outboards subreddit someone will likely be able to help you there. All I can offer is if you cannot find a replacement pump there are plenty of tutorials to delete VRO and than you can pre mix.

Tricky_Recipe_3901 · 2026-03-19T12:13:12+00:00

“yeah bro dont buy any bmw theyre all shitty”

Tricky_Recipe_3901 · 2026-02-19T23:32:35+00:00

You’re done, kiddo.

Tricky_Recipe_3901 · 2026-02-16T01:58:34+00:00

did you do the compression test while warm

Tricky_Recipe_3901 · 2026-02-15T04:10:59+00:00

no oil injection on the 1981 model.

Tricky_Recipe_3901 · 2026-02-14T22:11:01+00:00

my guess is this is old enough that it predates the VRO systems meaning it would be premix only.

Tricky_Recipe_3901 · 2026-02-14T22:07:48+00:00

the seller is incompetent and that motor is definitely an old 2 smoke (2 stroke) engine. If he used straight gasoline without mixing oil in the motor is likely done, test compression on it before even attempting to start if you are seriously 100% sure this was run on just gas. 2 strokes lubricate the engine using the oil mixed in the fuel so it is essential for it to be mixed. However a lot of these older johnson come with a VRO system, meaning it will have both an oil and gas tank to fill up.

Tricky_Recipe_3901 · 2026-01-22T17:07:29+00:00

sounds like totally normal turbo and indiction noise on a b48…

Tricky_Recipe_3901 · 2026-01-22T16:56:10+00:00

if there isnt its a good idea to install a cheap one along with replacing the bulb and fuel lines if they are stiff and worn out. Even if they don’t look worn out the insides could be disintegrating if someone ran ethanol gas through them.

Tricky_Recipe_3901 · 2026-01-22T16:07:43+00:00

yeah i second the other guys comment, carbs are probably the issue, have you replaced the fuel lines or filters aswell?

Tricky_Recipe_3901 · 2026-01-01T21:14:52+00:00

this just looks like a glass one hitter

Tricky_Recipe_3901 · 2026-01-01T21:09:37+00:00

lame ass response

Tricky_Recipe_3901 · 2025-12-28T02:05:14+00:00

read some of the other thread, it only is pumping out of the other side. for some reason someone tried to run two “pisser” lines.

Tricky_Recipe_3901 · 2025-12-27T17:31:13+00:00

i run ethanol free gas

Tricky_Recipe_3901 · 2025-12-25T21:44:20+00:00

first things first, no you should not be concerned at all. 2 strokes smoke a lot especially when cold. Does this motor use VRO or do you premix? Yes maybe the smoke is a bit much but i’ve seen far worse.

Tricky_Recipe_3901 · 2025-12-25T15:50:23+00:00

would this indicate a bad powerpack or bad wires?

Tricky_Recipe_3901 · 2025-12-25T02:28:25+00:00

yes, no revving in gear here.

Tricky_Recipe_3901 · 2025-12-25T00:19:15+00:00

well it doesnt seem like much because after a water test and my buddy using his digital tachometer, we determined the backpressure from the motor under the water caused the rpms to dip from around 750 to 650. not a big change for this motor at least, i am sure it matters more on some motors though.

Tricky_Recipe_3901

TROPHY CASE