Slight RPM hunting after a warm start

[edwinn]

Originally Posted by enslow

I don't think there is any difference between the top and [bottom] ports. For the 4T60 transmission you would have a vacuum line to the EVAP, FR, and vacuum modulator for the transmission. The 4T65e eliminated the vacuum modulator, so if that is your transmission, that may explain why one port is blocked.

Port blocked? enslow

Never noticed a trans vacuum modulator hose. What port is blocked? Do you mean that hard right-angle fitting that goes to the FPR? that looks like a port cap?


-Ed

[enslow]

Originally Posted by edwinn

Port blocked? enslow

Never noticed a trans vacuum modulator hose. What port is blocked? Do you mean that hard right-angle fitting that goes to the FPR? that looks like a port cap?


-Ed

Sorry, it looked at first glance that the top port was plugged. I saw the fitting at a closer glance.



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[edwinn]

Originally Posted by enslow

Sorry, it looked at first glance that the top port was plugged. I saw the fitting at a closer glance.

No problem.. add comments anytime, all are valuable.


Vacuum lines switched

Hope this isn't overkill, but the 'low angle' flash photo below had the tubes switched and presumably correct.
All three of those rubber fittings are dry-rotting and need to be replaced. All of them are NLA AFAIK.


Purge valve line is now on Top port, and FPR line on bottom. Maybe it doesn't make any difference?


A guy over at TurboBuick says he uses a CLEAR vac line to the FPR... to see any liquid in there.


Vacuum measurements

Hey.. dug up my old Vac gauge from the 80's and checked the two 1/2" ports. Both are reading 17.5 - 18 in Hg.





-Ed

[enslow]

If you choose to go with clear tubing, make absolutely it can take the vacuum without collapsing over time, especially as it gets warm. Nalgene tubing gets soft when hot.

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[edwinn]

New fuel pump installed

The new fuel pump module was installed last Monday but I didn't bother to look at it for a day or two. Instead.. test-drove it around town going to stores and running errands, etc.

See photo below of new pump module and locking ring.


New FP viewed through access panel in trunk.


First impression was that too much damage was done to the tank rim and mounting area.. which is now covered with white grease that the shop applied. I would have used shims to prevent the punch from striking the metal rim and plastic nearby. The shop said they had difficulty getting the old locking ring off.


Compare the photo above with the original weak and leaking FP module below.


The original FPM installed in Oct 1996 (17 years ago) when the car was built.


No leaks (so far)

Have been keeping an eye on it for a few days. The smell of fuel is pretty much gone.. and no visible leaks!!


How does it run?

The NEW fuel pump sounds strong and is more authoritative than the original one.. and the engine seems even more responsive than ever. I could feel it was more 'zippy' (hesitation gone) after the new spark plugs, and with the FP.. it seems to accelerate up through 2500 RPM more aggressively. Not sure if the start-up stumbling is gone yet. The weather is VERY cold now and I'm glad to have replaced the FP before winter.. for all the reasons previously mentioned.


It really wants to take off when the accelerator is pushed now.


-Ed