Weird loss of power at cruising speeds.

[PorscheGuy79]

I am having a new issue that’s a little unsettling. I recently found and reconnected a vacuum hose on the WUR that had worn off. This has made startups and idling much better. But now twice just on the highway at 3000rpms around 3rd/4th gear I have had a loss of power where the tach just dips down. I pump the gas and it backfires but starts up again. Any ideas on where’s I should start looking? Is it just a bad WUR?

‘79 SC. CIS 3.0

[T77911S]

you need to post pics of the WUR, and the vac hoses and where they are connected.

off the top of my head the 78 has the vacuum enrichment vac on the side of the WUR. that needs to goto manifold vacuum.

[PorscheGuy79]

Ah yes. Very important. The yellow circle indicates the hose that was unplugged but I have since reattached.

[T77911S]

you need to post the numbers on the WUR

that hose is the vacuum enrichment used for acceleration and WOT.
first, remove the hose with engine running and verify it has vacuum.
if not, the small round device it goes to is the thermo time valve (TTV). it is ONLY closed when cold and only for about 20 seconds. it helps with cold starts. remove the OTHER hose on the TTV and check for vacuum. if vacuum is NOT getting thru the TTV check for power to it. if it has power and it is CLOSED it is BAD. you can bypass if want. you live up north, it could really help cold starts in the winter but if it starts fine without then leave it bypassed if you want.

the vacuum goes to the side port on the 78 WUR.

to test the WUR you need fuel gauges.
you can try remove that hose at idle and see if the engine changes in how it runs.

I am surprised it was drivable with the hose removed.

[PorscheGuy79]

Thank you. That was helpful. It seems now the car will run just fine with the hoes replaced until it gets warm. Then the RPMs will hunt until it dies, usually appearing to be very rich. Sometimes backfiring when attempting to restart (yes I have a pop off). I am looking to get the tools to check the WUR. But I was curious if you have any instructions on how to bypass the TTV?

Also, I see 916 or 619 stamped into the top of my WUR if that helps.

[pete3799]

Is that motor original to the car? The hard fuel lines to the injectors were not used in 79.
May be that a previous owner swapped some CIS components or a different motor.
Post the engine numbers and someone here can tell you if they are correct.

My 79 (euro) number is 6390277 type 930/03

[SkiVT]

Your wur number should look like this 438 140 045. Look on the side closest to the passenger cabin. The last 3 digits vary by year/engine.

[T77911S]

hunting is too rich
remove the vac hose to the WUR and see if it stops it