1989 johnson 140 VRO no high speed

hello all!

Just installed a 1983 fuel pump and am running premixed gas. One problem to overcome was that the recommended pump did not have a fitting for the vacuum pulse. (This 1989 140 v4 does not appear to have the alternate 'bolt the fuel pump to the auxilliary position' that I have read about.) I fabbed a fuel motor mounting plate to bolt into the old vro mounts and used a brass 3/8 fitting over the central vacuum opening on the pump and then connected the vacuum pulse line to the fitting using an extension on the hose and a 90 elbow.
One glorious day 2 weeks ago I started her on the muffs and low and behold ... a running motor halleluiah!!

Chpt 2
Rented a cottage for the weekend. first it would not stay running. Then I got her running, launched and idled to the dock. First time I took her out I expectantly accelerated but would not pick up beyond a fast idle. Top speed was 8 mph .... (I know she'll do 35-40 at WOT).

Ran like that all weekend. If I leave throttle at WOT she'll overheat but ran for hours if throttle is left at 3/4 or so.

I am thinking either the pulse is insufficient for the fuel pump with the extra line and elbow so fuel delivery is insufficient. Seems like it should run for a short time til bowls are empty? Began wondering about the s.l.o.w. function. I checked the temp sensor wires when I got home and the starboard side was against the #1 spark wire. Read somewhere that might be the problem.

Also have replaced all the fuel line, bulb and filter.

Any comments out there?

Re: 1989 johnson 140 VRO no high speed

is it possibly a problem with an anti siphon valve?

Re: 1989 johnson 140 VRO no high speed

Just to tie up this thread for future reference.

I had the boat out yesterday and it ran very well. Power was consistant right up to WOT. Since the first post in this thread I have been out twice with a co-driver and spent time hanging over the back of the boat with a timing light trying to verify ignition spark under load. Consistant spark was difficult to verify as it seemed that either I or the timing light was bouncing around most of the time

Last week I removed all the coils and cleaned all connections with electrical contact cleaner. I also removed any oxidation from all contact areas with fine emery paper. I discovered missing/misplaced washers and star fasteners on the mounting bolts for the coils that would indicate that someone had been 'in there' and done a sloppy job with reassembly. Also interesting is that the parts shop had recommended 4" spark plug wire replacements when 9" are barely long enough to reach from coil to spark plug (coil posts face away from the cyls so wires have to loop around).
When I had the coils off I found that one mounting post for the lower port coil had been painted from factory with the Johnson high heat enamel (on the ground side of the coil!). I suspect somone over the years had swapped out the coils with a replacement part and had to mount them facing the other direction for clearance. Unfortunately, that put the ground of the coil on the painted mount. The ground could have been made through the bolt into the threaded portion I suppose but the metal plate on the coil would have useless as ground for that cylinder. Anyway, I spent a bit of time sanding off the paint until contacts were all good and clean.
Also cleaned up contacts on the tan temp sensor wire (S.L.O.W.) and on the port twmp sensor (fast start wire).

I was fully prepared yesterday to spend the day running and troubleshooting as that has been my M.O. alll year. When we took off from launch I was thrilled with performance! I don't have a tach (my next get) so I can't verify rpm but it ran without misses or pops and topped out at 38 MPH on gps. Either the S.L.O.W. system was limiting revs or spark had degraded to the point that at least one cyl was cutting out. Keeping my fingers crossed that this good performance remains consistant.

Re: 1989 johnson 140 VRO no high speed

good find, and thanks for updating us.

Re: 1989 johnson 140 VRO no high speed

It's frustrating to find an old thread that deals with your problem, read through the posts and find it stops without being resolved. I am sure in some cases owners simply give up on their machines. However, those who finally diagnose a problem should tie up the loose ends on the forum for future users