front 044 - 2nd failure... diagnosing fault?

[Ronnie's.930]

Originally Posted by reclino

One way to put it is these pumps don't like to suck.

So in other words, the pumps are NOT Paul?!

[JFairman]

Originally Posted by reclino

I have googled around a bit more today and roller cell pumps like the Bosch 044 are very sensitive to cavitation due to restriction on the inlet side. One way to put it is these pumps don't like to suck. Looking at my inlet strainer I just don't think it's large enough to support the flow. One other contributing factor is the vapor pressure of ethenol is lower than gas. This means gas/ethenol blends are more prone to cavitation. Cavitation on the inlet side of pumps will kill the pump.
David

Good points you posted that are good to know.

Before I removed my gas tank to restore it a few years ago I had to drain it best I could.
I removed the fuel inlet line at the fuel head and stuffed it into a 4 foot long hose and put the other end of that hose into a 2.5gallon jug and turned on the 044 fuel pumps.

An approximately 14mm diameter stream of gas came shooting out of that hose like a garden hose. It filled the jug quickly so I don't think the original fuel strainer in my '87 gas tank restricts the fuel flow too much for 044 fuel pumps.

That information may have been aimed at the guys with hot rodded Asian 4 cylinder cars. A lot of those guys use Bosch 044 pumps and the gas tank fuel pick up strainers are probably smaller in those cars than the one in a 930 tank.

[Alexm930]

Paul, just my 2 cents here but I would not use crimp connectors without soldering & heat shrink at the connection.

[pkabush]

Originally Posted by Alexm930

Paul, just my 2 cents here but I would not use crimp connectors without soldering & heat shrink at the connection.

Agreed. As Ronnie pointed out, it's probably not the problem. It's likely to turn into one down the road though. I was pulling my hair out chasing an intermittent wiring issue on my Dodge truck. Turned out to be a ****ty crimp connection by the p/o at the f/p.
Solder and s/w are pretty bomb proof.
Good luck. LUK the outcome.

[Jeff NJ]

When done correctly, crimping is a more reliable, better conducting method for connecting wires compared to soldering . It is also considerably easier to do correctly than soldering.

Marine Wire and Cable: Crimping vs Soldering Marine Cable and Wire Connectors

[Ronnie's.930]

^^^

I used to solder everything, but never got very good at it and always hated how slow the process was (for me), so gave that up many years ago after reading about the superiority of good crimped connections, and of course, it is much easier and quicker. Now I only solder large cable connections (like car battery cables). I don't like crimped insulators however, so always use heat shrink instead.

Paul, this is how a real man crimps and insulates - getcha suuuummmmm!

[WinRice]

Paul,

I haven't been on in awhile, work is consuming my life, but here's my 2 cents.

Good (non knockoff) pumps die from a couple of things, too much heat on the motor, and debris through the pump section. Sounds like your problem fits in the overheat category. JFairman outlined the pump function nicely, so to summarize:

1. Not enough fuel flow, motor isn't cooled and dies.
2. Restriction on the suction side the pump works too hard and overheats.
3. Restriction on the pressure side, pump works too hard, starts to bypass, cavitate and overheats.
4. Wiring problem that keeps the pump from getting full voltage, causing the motor to strain and overheat.


An overloaded fuel pump pulls more amps than when it's operating normally, and that's what causes the heat. When you install the new pump, buy or borrow an ammeter and hook it in series with the new pump. Put a volt meter across the pump. Fire the car up and let it run, monitoring the amp draw and voltage drop, and see what it's running cold and warm. From memory, the pump would draw about 11-12 amps under constant load. Maybe JFairman has better numbers. Measure the voltage across the battery and compare it to the voltage across the pump.

[WinRice]

Originally Posted by Jeff NJ

When done correctly, crimping is a more reliable, better conducting method for connecting wires compared to soldering . It is also considerably easier to do correctly than soldering.

Marine Wire and Cable: Crimping vs Soldering Marine Cable and Wire Connectors

I'm not saying one is superior to the other, that's about as a bad as the oil wars, but that article has a few fallacies.

1. No matter how perfect the crimp is, the solder will wick through the voids.
2. Most terminals already have a lead/tin coating on them to start with, and if you crimp and solder, the solder only fills in the voids and doesn't add resistance.
3. Every good solder joint starts with a good mechanical connection.
4. Anybody can solder well, but most start with a cheap 40 watt Radio Shack soldering iron when you really need a 200 - 300 watt gun so it heats fast and flows well.

[krasuskyp]

thanks Win - will try those suggestions hopefully today when John comes by

[WinRice]

One thing I forgot to add, a high load on the pump and the amp draw usually goes up, when a pump cavitates, it's moving air and vapor and the amp draw usually goes down. YMMV