Slight RPM hunting after a warm start

[enslow]

Maybe I was looking at the wrong video, but I couldn't tell when you removed the vacuum line.

Does the fuel pressure snap up instantly when the vacuum line is removed? Is it steady with the vacuum line removed?

The vacuum modulates the fuel pressure. No vacuum means you will have full fuel pressure. If your vacuum itself is jittery, it will cause the fuel pressure to be jittery.

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[edwinn]

Originally Posted by enslow

I couldn't tell when you removed the vacuum line. Does the fuel pressure snap up instantly when the vacuum line is removed? Is it steady with the vacuum line removed? The vacuum modulates the fuel pressure. No vacuum means you will have full fuel pressure. If your vacuum itself is jittery, it will cause the fuel pressure to be jittery.

Thanks for the reply.. video #2 above should be labeled "after FPR vac line pulled." Yes.. the pressure snaps up instantly but the gauge flutters a LOT. I'm questioning if that's a cheap gauge.. and only good for static pressure measurements? Is the pressure REALLY flipping all over the place? is the needle under-damped? or is the fuel pump about had it?

See gauge's wild respond to an Ignition On transient: http://home.comcast.net/~edwinn/97_R...n_on_click.mp4 (300 KB)


Ok then.... the vacuum line is pulled from the FPR in video #2 above, and the pressure is still jittery.


-Ed

[edwinn]

Got into the trunk today

One of the issues (along with idle instability) the dealer guys looked for was smell of Fuel from LR wheel-well. Sometimes it's faint, and other times it's strong. Since the weather warmed up, I decided to get into the trunk today and open the fuel pump cover to inspect the seal and connections. Good move!!


Fuel pump exposed

The FP cover came off without much trouble using two wooden clothespins taken apart to form wedges. In just 2 or 3 mins the cover popped-off with no damage to the paint.. or the cover gasket/seal.


Wooden shims used to get under the lid. This image is a video screen-cap.


Below is a view of the FP with obvious signs of fuel leakage. There was a strong smell of Fuel under there!!


First look at top of fuel sender. There were signs of leaking and sloshing.


Very productive day today.

-Ed

[edwinn]

FP area prep

Here's a photo of FP area scrub #1 using an old paint brush and Armour-All car wash solution (in a blue plastic coffee container.) It was still drying at dinner time yesterday. Will be going in there again for another inspection and scrub.


First scrub of the plastic fuel tank around the fuel sender unit.


What's the idea with the center port OPEN on the FP? It vents from there with no tube or hose?


Tank vent

There's a tank vent or vapor port aft of the FP under the trunk floor. Notice the tubing date.. Sept 1996.


Vent on top of fuel tank. I'd like to drop the tank and check it all out, but that's a BIG job.


I'll need to figure out what that unit it.. Vapor or Vent? Below is a snapshot from the Service Manual Vol. 2 of 3.


Not sure if this is a general diagram.. for Olds, or for Buick?


Replacement fuel pumps

I've found replacement FPs from Carter, and two from Delphi. They all have different pressure ratings: Carter 105 psi, Delphi 43 psi & 60 psi. How best to match up FP pressure rating with pressure regulator specs, etc? There was NO Fuel Pressure spec found in all THREE Service Manual volumes. Where can one find the Spec for Fuel Pressure?


Please jump in and comment. This isn't a lecture but a discussion.


-Ed

[maxwedge]

Nice job cleaning up, 47 psi is your operating minimum so 60 is good as the press. reg. will handle the chores, stay with a Delphi pump. BTW a brass drift is what I use to rotate the lock ring, try and get a new one( ring), and lightly lube everything on re-installation.

[edwinn]

Originally Posted by maxwedge

Nice job cleaning up, 47 psi is your operating minimum so 60 is good as the press. reg. will handle the chores, stay with a Delphi pump. BTW a brass drift is what I use to rotate the lock ring, try and get a new one( ring), and lightly lube everything on re-installation.

Great reply max!

Sounds like the Delphi rated at 460 kpa will do the job.

One thing that's troubling! The Fuel Sender Unit harness/connector has only TWO wires. How can the fuel level sensor operate with just a hot and ground? or is the tank grounded?


-Ed

[enslow]

Originally Posted by edwinn

Thanks for the reply.. video #2 above should be labeled "after FPR vac line pulled." Yes.. the pressure snaps up instantly but the gauge flutters a LOT. I'm questioning if that's a cheap gauge.. and only good for static pressure measurements? Is the pressure REALLY flipping all over the place? is the needle under-damped? or is the fuel pump about had it?

See gauge's wild respond to an Ignition On transient: http://home.comcast.net/~edwinn/97_R...n_on_click.mp4 (300 KB)


Ok then.... the vacuum line is pulled from the FPR in video #2 above, and the pressure is still jittery.


-Ed

ok, when I replied, I didn't see your reply #15 for some reason. I'd also agree that it's your fuel pump. If your fuel gauge is capable of being steady to measure a static pressure, it should be good to measure a dynamic pressure.

Just be thankful your access to the fuel pump is through the trunk. I'd have to drop my fuel tank.

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[Tech II]

ED, just want to prepare your for the worse case scenario....

Ran into this only once......customer needed a new fuel pump....as you can see, that ring can get pretty rusty.....

I vacuumed the area.....the ring would not budge.....let PB Blaster work it's magic......

As Max said, a brass drift usually works.....I couldn't budge it.....and I had the special tool which fit around all the ears, so all the ears would be getting pressure to move at the same time.....so with my breaker bar on the tool, I gave it a few whacks with my 5#'er....finally it moved....or so I thought.....the ring, that is imbedded in the top of the plastic gave before the upper ring did......now, I had to get a new tank from a local bone yard....and dropping the tank was not fun.....

Funny on most GM's, that 3rd port has a plastic line for the emissions system....just a different design......On that harness there has to be a third line for the fuel sender, usually purple with a smaller wire size....apparently this design shares the ground for the pump and sender...

[edwinn]

Originally Posted by Tech II

ED, just want to prepare your for the worse case scenario....Ran into this only once......customer needed a new fuel pump....as you can see, that ring can get pretty rusty.....I vacuumed the area.....the ring would not budge.....let PB Blaster work it's magic......

As Max said, a brass drift usually works.....I couldn't budge it.....and I had the special tool which fit around all the ears, so all the ears would be getting pressure to move at the same time.....so with my breaker bar on the tool, I gave it a few whacks with my 5#'er....finally it moved....or so I thought.....the ring, that is imbedded in the top of the plastic gave before the upper ring did......now, I had to get a new tank from a local bone yard....and dropping the tank was not fun.....

Funny on most GM's, that 3rd port has a plastic line for the emissions system....just a different design......On that harness there has to be a third line for the fuel sender, usually purple with a smaller wire size....apparently this design shares the ground for the pump and sender...

New parts

Bought a new Fuel Sending Unit and a Locking Ring (or cam) from Delcoline today.. so OEM replacement, not a Delphi. The distributor had the FP ready for pickup in a few hours (thanks guys.) The other brands from NAPA had to be shipped from some warehouse. Also got a new Wix (NAPA) fuel filter.

I see what you mean about a frozen cam ring. What concerns me most is... what condition will the tank 'metal edge' be in after the FP is removed, and did rust cause the rubber seal to leak?


See... there may be rust on the EDGE below. Should Permatex sealant be used?


This photo shows a few drops of 'Liquid Wrench' dripped on the locking tabs. The tank rim is rusting.


As for knocking the retaining ring lose.. the tabs got some 'rust release' juice dripped on them this morning.. and the ring-to-plastic pump got some WD40. After that soaked for a while, I poured some car wash solution over the ring (not the connector or open port) to rinse the chemicals down.

The strategy for tomorrow morning is.. to 'tap' or 'rap' the tabs several times, and tap the ring 'down' a few times with the punch tool (bought a brass one) to loosen the rusted interfaces. Then I think it will rotate and unlock... that is, after a lot of mild-to-medium taps/raps. All this has to happen without crap or contamination falling into the tank.


A very rusted tank locking tab... trying to get some penetrating oil under there.


Turns out the other two wires were below the BLK and GRY ones.


In this view, WD-40 is sprayed between the locking ring and plastic FP body.


The good new is

Applying liquid auto polish to the trunk floor really spiffed it up! The surface is slick and shiny. Now i need to search for a method to treat mildewed carpet/insulation.


-Ed

[edwinn]

Fuel Module replacement Fail!!

Was all set to replace the FP today and got started early before noon. It became obvious that a brass punch and 24oz ball peen hammer were NOT going to break the cam (retainer) ring lose. The tabs were bending DOWN because the punch was at too high of an angle.


FP area all prepped to replace the fuel sending unit.


Compare that with the photo when the access cover was first removed. There were a strong smell of fuel and the FP seal was leaking!


A view of the FP when access cover was first removed.


FSU removal tool

The tank rim may be rusted or deteriorated, and I didn't want to bang the crap out it. An illustration of the correct 'spanner tool' was found in the Service Manuals.





Have a shop replace the FP

Have decided to call my local shop and have them replace Fuel Sender, and the fuel filter at the same time. There was just TOO much fuel fumes in the garage, and banging on the tank with a hammer was causing a disturbance. Then there was the issue of disposal of the old and gas-soaked parts to deal with. Too much fumes, man!


Contaminated fittings

The shop manual says to "clean and inspect the O-ring sealing surfaces" and "clean fuel pipe and hose connections.. and areas around the connections." Unfortunately there are no 'before' photos, but the fittings had too much dirt in them and the retainer clips were also contaminated. The photo below shows the clips after hitting them with solvent and an acid brush.


Fuel line retainers scrubbed and ready to reconnect to the FP.


Here they are back on the original FP fittings..


Fuel line retainers back on the fittings.


Lines have dirt inside

Running cotton swabs into the lines.. they had significant contamination even three inches into the tube.For that reason, the fuel filter needs to be replaced. A really GOOD job would be to drop the tank, flush it out and reinstall and replace the tubes.


Fuel line had quite a bit a dirt inside.. even three inches past the fittings.


So the original Fuel Pump is reconnected with fittings decontaminated. Off to the shop where they have the right tools.. and can deal with petrol fumes.



-Ed

[edwinn]

Originally Posted by rkvons

How's your fuel filter?

The fuel filter was last changed in Oct 2007 at 100,410 miles. After popping-off the lines on the Fuel Sending Unit, and seeing the dirt inside the connections.. and even dirt 2-3 inches up the tubes.. I'm convinced the fuel filter needs changing every four years or so, especially for older cars.


Looking in the Return fuel line (too dark in there for the camera.) There was greasy dirt inside the fittings.



This is the condition of the Return connection AFTER the retainer was removed/scrubbed and the male fitting wiped.


The shop manual say `not to change the fuel filter unless it's obstructed,´ but I happen to think it should be changed roughly in 6 yrs, 4 yrs, 4 yrs.. or even 5 yrs, 4 yrs, 3 yrs. The history of this vehicle has been new FF after 11 yrs, and 6 yrs.



I happen to like the Wix line of filters sold as NAPA Gold series.


-Ed

[edwinn]

Vacuum measurements

There are TWO 1/2" dia vacuum ports of the front of the throttle body, and they both measure 17-1/2 inHg.

During snap-throttles, the vacuum instantly dropped from 17.5 to 10-8 in. Looking at a the eVap diagram below printed by the dealer, I see the vacuum line from the purge switch goes to the TOP 1/2" vacuum port. My vac lines were reversed!! that is, the FPR hose was on the Top port.

See the dashed red line below.


Diagram from dealer shows vacuum line from evap switch goes to the top TB port. My vac lines were reversed.


1/2 inch lines reversed

This is incorrect according to the drawing. See how the inline rubber fitting is starting to crack.


Lower TB port with Vacuum Gauge probe shoved into it, should be on the Upper TB port.


The vac lines have been like that at least since mid 2011 when the vacuum purge switch was replaced in Sunnyvale. Maybe it doesn't make any difference. Changing the lines around to the correct positions did solve the warm-start stumbling.

QUESTION: What is the difference (in function) between the 1/2" upper and lower TB Vac ports??

Replacement Vac fittings

Would REALLY like to replace the FPR vacuum line and right-angle fittings.. especially the 1/2" to 5/32" bend on the right. It's getting crisp and flaking!


Original FPR vacuum fittings and small diameter semi-rigid line.


Will be coming up was a new vac line assembly.. probably with a section of clear 5/32" tubing (to look for liquid fuel or dirt inside) transitioning to a 1/2" rubber vac hose. Any suggestions on tubing and 0.158" to 0.50" inline adapters?


-Ed

[maxwedge]

Great pics, but how did this happen?

[enslow]

I don't think there is any difference between the top and 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.

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[edwinn]

Originally Posted by maxwedge

Great pics, but how did this happen?

Thanks.. the hoses have been like that for a very long time, at least since a new purge solenoid was installed mid-2011 in Sunnyvale. The upper port is recessed further into the TB but they seem to be on the same air circuit. Notice headers on the vacuum line diagram. That page was pulled-up after inputting the VIN number, so it's probably correct. I still want to replace the Vac line and fittings to the FPR.


-Ed