Golan fuel filter cleaned

I cleaned the fuel filter.


Most junk was around the small metal screen on the intake side, even though this stuff looks like is fine enough to pass that screen. I guess due to the diagonal installation position, the stuff slowly drips off the main filter screen and collects on these edges.

Another shot of the intake side

Exit side looks clean, except...

For these particles under the O-ring. So apparently these particles are small enough to pass the filter.

I soaked the filter screen in paint thinner & rinsed it under running water, but I didn't see any dirt coming off it.

All assembled, including the pipe fittings

Mounting point

Videos

A couple of videos demonstrating the problem. On idle, but the symptoms look the same on the highway as well.

91 Firebird TBI, bad idle, starting w/ charger off

91 Firebird TBI, bad idle, starting w/ charger off, w/ EST bypass

(not embedding the clips because loading them would take forever)

More engine trouble

So after the last datalogging session, I did another test drive.

Everything mostly normal, except..... when cruising at 80-100 km/h (50-60 mph), the engine started acting up like crazy. Stalling, choking, tachometer jumping up and down, etc. Not just the tachometer and engine, but the car itself would also slow down, accelerate and "jerk back and forth" at the same pace with the engine. So apparently the TCC was locked when this was happening.

I pulled out from the "highway", stopped the engine and tried to start again. It started roughly; choking, stalling, etc. After detaching the EST bypass cable, I was able to drive it home carefully. The engine seemed to run better with the EST bypass disconnected, but I can't tell if it was normal for that condition. The exhaust sound was more "bubbly", and I didn't see the tachometer jumping around anymore.

Datalogging, ignition/electrical bugs

I think I've spotted the gremlins in action.

I took some data logs using the venerable WinALDL during my test drives (on 2013-05-04 and today, 2013-05-08), but I only bothered to analyze them now. The graphing software I used for these pics is called ALDLView.

Logs from 2013-05-04

This time I had the crappy ignition coil in.

The battery voltage drops intermittently and often. I suspect these are the same incidents when I've seen the SES light flash and/or the tachometer jump wildly.

If we add more variables and zoom in, we'll see that all values drop to zero simultaneously. Here are Speed (VSS), MAP, RPM and O2 readings in addition to Battery Voltage.

In the second incident, the VSS jumps to 180, but in most of these it drops to zero as well. This matches what I've seen the speedometer do: most of the time it shows a realistic value, but a couple of times it's jumped up randomly.

Here's a sample of the "DRP Occurred" signal (Distributor Reference Pulse). I find it odd that it DRP frequency doesn't correlate with engine RPM.

Logs from 2013-05-08

I made another 16 km (10 mi) test drive today. This is after putting the original ignition coil back in & replacing the vac hoses.

There were only 2 voltage drops, and they happened while the car was still idling on the lot (pic below, speed zero, CTS rising). All in all performance felt "normal", there were some random tachometer jerks still.

2nd part of the test drive. The battery voltage didn't drop at all (according to the ECM), so ALDLView scales the white line differently.

I saw one SES flash, though. This happened on WOT (wide open throttle) acceleration in the middle of the graph.

Here's a closeup of the WOT part, i.e. where TPS (throttle position sensor) jumps to 100%. The speedometer also jumped almost 45 degrees upwards and the tach was acting up. The car accelerated nevertheless (yay). Right before flooring the pedal, I saw the tach jump a couple of times, this might match the two minor voltage drops just before the WOT part.

Maybe the acceleration itself shook some contacts loose and this caused the ECM to reset for a short moment?

Also, here's another graph of the DRP flag:

Odometer: 225 974 miles.

Vacuum hoses replaced

I decided to replace the vacuum hoses to be on the safe side. However.... even though I specifically asked for vacuum hose, and the clerk at my local (read: only) parts store acknowledged that I was, indeed, requesting vacuum hose, only after returning home did I realize that I'd been sold...... fuel hose. Apparently I should have checked the markings on the hose at the counter. WTF is wrong with people?

I installed the new hoses nevertheless, since some of the old vacuum lines were really worn out.

Old hoses:

• 5/32 GM6148M 042490 ADP (~ 4mm)
• 5/32 GM6148M 042490 PRC (~ 4mm)
• Some unlabeled piece (5-6 mm?), between intake manifold and a valve that connects to the A/C vacuum system

New hoses:

• MULTI FUEL GATES AUTO MASTER 4 MM MULTI CARBURANT UNIVERSALKRAFTSTOFF GATES 3225 (or "322E"?)  (4 mm)
• MULTI FUEL GATES AUTO MASTER 6 mm MULTI CARBURANT UNIVERSALKRAFTSTOFF GATES 3225 6 mm UNIVERSELE BRANDSTOFF MULTI CARBURANTE CS112811 X2

The flexible vacuum "pipes" that connect e.g the MAP sensor and the EGR solenoid I left in place.

Odometer: 225 974 miles