Losing Power

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ttl08
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Losing Power

Post by ttl08 » Wed Aug 21, 2013 2:23 pm

I have a fuel injected 1978 Super Beetle convertible. Engine rebuilt about 5,000 miles ago. Ran fine until just recently. With engine at operating temperature and well into a drive, engine will start to choke and lose power. Won't stall but no power. After about 5 minutes of this, it will right itself and run fine. Also will right itself if I shut it off and let it cool off. Any suggestions? Thanks. TTL08

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Amskeptic
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Re: Losing Power

Post by Amskeptic » Thu Aug 22, 2013 8:14 am

ttl08 wrote:I have a fuel injected 1978 Super Beetle convertible. Engine rebuilt about 5,000 miles ago. Ran fine until just recently. With engine at operating temperature and well into a drive, engine will start to choke and lose power. Won't stall but no power. After about 5 minutes of this, it will right itself and run fine. Also will right itself if I shut it off and let it cool off. Any suggestions? Thanks. TTL08
Losing power is a serious warning sign.

A) Your engine is going to die.

B) Something stupid needs to be fixed.

Therefore, always investigate because nobody knows if it is serious or not until they do investigate.

Your job here is to get the engine to the unhappy point, and do your diagnostics while it is feeling punk.
You said that it "rights itself" while driving which means that you do NOT have a tight valve suddenly killing a cylinder when it cannot close all the way when hot, but I would check my valve adjustments first anyway. Let us know if you have any tight valves.

I doubt that you have a temp sensor going rogue at hot temperatures then as the engine drops out and cools down it recovers, but hey, check sensor readings cold against the Bentley.

Fuel tank/filter obstructions can "go away" after sitting, then junk clogs under fuel flow, but again, you don't drive through that sort of symptom.

Fuel pumps can stumble when electrically hot, coils can break down when electrically hot, but you wrote that you can drive through this symptom.

I would do a vacuum hose/electrical ground check, followed by a deluxe tune-up with aforementioned valve adjustment, gap points if you have them, timing, and have you ever adjusted mixture on an L-Jet engine? My intuition is suggesting that you ensure that the fuel mixture is well within the "window" that L-Jet has. L-Jet is rude when its parameters are exceeded.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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ruckman101
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Re: Losing Power

Post by ruckman101 » Thu Aug 22, 2013 8:44 am

A failing condenser?

neal
The slipper has no teeth.

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Amskeptic
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Re: Losing Power

Post by Amskeptic » Thu Aug 22, 2013 8:49 am

ruckman101 wrote:A failing condenser?

neal
Condensors act like bad gas. They cause hard starting, popping and bucking and spits and backfires.

This is an interesting one, in that the symptoms clear up magically . . . ?
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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ruckman101
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Location: Up next to a volcano.
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Re: Losing Power

Post by ruckman101 » Thu Aug 22, 2013 9:34 am

The failing coil experience seemed identical to me as a failing condenser, but it was a lack of spark that I remember in both instances, which now that I think of it sounds different than this case, as it brought me to a halt, cooled, and restarted.

neal
The slipper has no teeth.

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