on its face

[Jules Dielen]

technical question. Got my S90 with solex solid shaft 40P11 carbs out for a drive after a 3 month slumber in the garage (Arizona summer...), it fired up after the 4th try and idled well. Took it out and took it slow for a few miles to warm it up. After engine temp was up a bit, i accelerated, all was fine until I hit 3000rpm, then it lost power and fell on its face. I took my foot off the accelerator, and all was ok again. gentle acceleration is fine, but when i depress the throttle anything past 30-40% it has no power, even below 3000rpm. I carefully (slowly) drove it home, and did the same in the garage with the car in neutral, same thing happens. If i depress the throttle too far, it sounds like it gets no fuel.

My initial thinking is maybe bad accelerator pumps? My last 'carb issue' ended up being my ignition. Any ideas?

Thank you

[Harold Singh]

Jules,

I’m sure you will hear to start with a standard tune before moving to diagnostics. I thought I’d beat everyone to it to break it to you easy! Good luck!

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[Martin Benade]

Last weekend I had somewhat similar symptoms, turned out the point gap had closed up almost completely- ran OK under 3000, terrible above. The gap must have been very small for a long time, but 30 minutes on the freeway brought it to a critical "point". Gap wasn't too sensitive probably due to my overkill MDS box. It was a trip to the jewelry store for an anniversary jewel for my wife. The owner asked if she could take a picture of my car. Several hours later my daughter saw it on Instagram captioned "pretty little visitor in our lot today" and 60 likes. I was surprised.

[Adam Wright]

Might also be a floaty clogging one of the jets, only hits when you call for lots of gas.

[John Brooks]

Bad condenser if you still have one, or the power wire to the msd

[Joris Koning]

Plugged accelerator jets? Remove the carb top and see if they squirt when you bit the linkage. They should be aimed at the point where the butterfly opens

[Geoff Fleming]

Main jets control power from 3,000rpm up... check all four for blockage.

[C J Murray]

Fuel pump? A very weak fuel pump will do exactly that. Put a level gauge on it and see if high rpm sucks the float bowl dry.

Ignition is a possibility also.

Usually clogged jets are idle jets because they are much smaller than the mains but Geoff is correct that mains would be causing problems over 3k rpm. A clogged main would make the car run poorly but still have some power.

Accelerator pumps are not the cause.

[Jules Dielen]

Thank you for the feedback gents. i will start with the easiest one (condenser) and then dig deeper from there! The car just had a tune up maybe 800 miles ago and ran like a scared monkey when i drove it last in spring.

[Norm Miller]

Adjust the points and test it first.

[Jon Schmid]

Late to the party but regarding condensers, my experiences are thus: 1. When they go bad, the engine just quits. It might turn over, but that's it. 2. The "new" Bosch units (6V in my case) are cr@p. My last one didn't even make 1000 miles. The guy that did the tuneup felt so bad he gave me his last German made one, which I keep as a spare so I can hang onto it for as long as possible. Just my $0.02--I hope you find the fault quickly, and good luck.

[David Jones]

Classic fuel starvation symptom. I would go for a main jet being restricted as it is at or above 3K rpm as Geoff and Adam mentioned. Also hard to detect which cylinder, as once you back off they all cool down equally. You could try the technique of driving it on a long straight quiet piece of road at full throttle then when it has run for a maybe 5 seconds with the engine at the reduced power symptom just shut it off with the ignition and stop and then use an IR gun on the exhaust pipes. Compare 1 with 3 at the base of the heat exchanger and 2 with 4 where they leave the heads. If one is significantly cooler than the other then you know which side to work on. If it is a common problem with the fuel system then all 4 will be cooler than normal and suspect a fuel restriction in the tank to pump area.

[Greg Scallon]

Jules,
All these suggestions are probably more likely to be correct than mine, but I do know that when my Optima batteries have been very close to dead, they will start the car but then one of the symptoms I can feel on the road is the engine cutting out and coughing at high rpms. Just a thought as you said the car recently came out of a slumber. Maybe your battery tender cooked the battery somehow.

Good luck figuring it out.
-Greg

[Jules Dielen]

Thank you Greg, i'll do a quick load test on the battery as well. It's been on my Ctek tender during summer.

[C J Murray]

Long shot...do you have an electric pump on the car for starting? Drive the car with that turned on to see if that corrects the problem.