New Stock Fuel Pump - Or Aftermarket?

[benro2]

Well, tonight was a bit of a bummer - my car decided to not start, luckily while I was at a Woolies petrol station so I had a paper and food while I waited for the NRMA guy to get there

He reckons it's the fuel pump - he banged the petrol tank a few times and then the car started properly - but he said it's basically a ticking time bomb and to take it straight to the garage. I took it home (it was about midnight) so now I need to source either a stock fuel pump (new or second hand) or a decent (cheap) aftermarket one.

Does anyone know how much a new stock fuel pump is and where to get one quickly? Alternatively, second hand in good condition?

If I go aftermarket, which pumps are a straight fit and run silently, and won't change fuel pressures, etc.? Basically an exact replica of the stocker if possible! I'm just going to take the car to a garage and get them to do all this, so I need minimised labour costs

I found a couple on ebay - any good?

http://cgi.ebay.com.au/ws/eBayISAPI.dll?Vi...em=310151808080

http://cgi.ebay.com.au/ws/eBayISAPI.dll?Vi...em=140331775778

Should I also replace the fuel filter at the same time? About how much are these and where can I find them?

Also, let me know what you think of my theory: I tried to sell my car some time back and it was basically sitting undriven for a bit over 3 months, at which point the battery died so I got it replaced. The guy who owned the workshop got his idiot apprentice to change the battery over and when he connected the new one, he blew a couple of fuses, and I suspect, a few motors in the process... This is what I'm not sure about: ever since then, I have had all sorts of electrical problems. Before then, the car basically never had any problems whatsoever. But after then, in the last year or so I have had both windscreen washer pumps blow, left mirror folding motor blow, left Philips headlight (2-3 yrs old) blow, ABS fuse blow, weird problems with the climate control, and now this dodgy fuel pump. What do you think? Did the apprentice do something to cause all this? Say to the car's alternator?

I've checked for raised voltages during running/idle/off and they're all fine. However, apparently it is possible for a couple of things to go wrong with the alternator that won't be detected by a multimeter (diodes? rectifiers? windings? one of these - can't remember) that I'll need a CRO (Cathode Ray Oscilloscope - I think ) to detect. Who is likely to have one of those? These electrical problems are really starting to get annoying, not to mention expensive...

Edited July 7, 2009 by benro2

[2LV8ETR]

A stock fuel pump will probably cost you a hell of a lot more than an aftermarket one. If you were to buy a second hand one, you may only get a limited amount of use from it before it too crashes and burns - it's a crapshoot.

I would personally go for the aftermarket. I know a lot of people hang shit on the Walbro, but as long as you don't get a Chinese knock-off it'll be a good replacement for the stock pump. If you can get a new genuine pump for less than the Walbro, then you're a lucky man. I run one (455lph) and so does my BIL, and neither of us has had issues.

As far as your electrical gremlins are concerned, I don't believe that a battery change could cause the issues that you're having. If your charging inside the required parameters then all should be good. I would like to say that the issues are just coincidental, but that sounds a little too far fetched. I dunno man, it's a weird one for sure.

[benro2]

As far as your electrical gremlins are concerned, I don't believe that a battery change could cause the issues that you're having. If your charging inside the required parameters then all should be good. I would like to say that the issues are just coincidental, but that sounds a little too far fetched. I dunno man, it's a weird one for sure.

Yep, it is a little weird to be coincidental. What do you mean by "required parameters"? I was standing near the guy when he did it - I think he must have connected it backwards or something - normally fuses don't blow when you change the battery right? So say he did in fact reverse the terminals, that could have shorted out one of the diodes/rectifiers/windings on the alternator, leading to spikes in the charge that are undetectable by a multimeter but stuffs electrical equipment? That's what I suspect! I know I have no way of proving it was him, but I just want to remove the source of the problems!

As for the fuel pump, Scott's Auto One apparently have a direct fit aftermarket replacement for about $250 shipped, deliverable in 1 day. Sounds like the go?

Alternatively, I might ask UltraTune (where I'm having the 110k service done next week) to see if they can order one in, but AFAIK they actually get their stuff from Scotties anyway...

[2LV8ETR]

By required parameters I mean the output voltage and current capacity of the alternator.

The actual output voltage produced by the charging system will vary depending on temperature and load, but will typically be about 1.5 to 2 volts higher than battery voltage. At idle, most charging systems will produce 13.8 to 15.3 volts with no lights or accessories on. This can be measured by connecting the positive (+) and negative (-) test leads of a voltmeter to the battery posts while the engine is running.

Current (amperage) on the other hand, is how much current the charging system produces at a specified voltage. Your alternator should produce up to 120 to 155 amps. Current output increases with engine rpm, from around 20 to 30 amps at idle up to the unit's maximum output at 2,500 RPM or higher. Charging output can be measured with an inductive amp probe clamped around the BAT (B+) wire that connects to the alternator. It can also be measured on an alternator bench tester by an auto electrician.

One of the most common causes of charging problems is the failure of one or more diodes in the alternator. Alternators have six diodes (three negative and three positive) that convert the alternating current (AC) to direct current (DC). They are called a diode trio because each negative diode is paired with a positive diode.

When the engine is running, charging current from the alternator flows through the diode trio via the BAT (B+) connection on the back of the alternator. A little current also flows through the charging light indicator circuit. When the alternator is charging, the diode trio supplies voltage to the ground side of the indicator light. This offsets the battery voltage applied to the positive side of the light, causing the light to go out once the engine starts. If the alternator stops charging, current flows though the light circuit from the positive side causing the charging system warning light to come on.

If one of the diodes fails, it may cause the charging system indicator light to glow dimly. If two or more diodes fail, the light will get brighter. At the same time, the feedback current from the diode trio will reduce the alternator's ability to produce current. So the more diodes that fail, the less power the alternator will generate.

A bad connection or open circuit between the alternator output terminal and the positive battery terminal will force the charging current to follow a parallel route through the diode trio and out of the alternator. This heavier than normal current flow through the diodes will cause them to overheat and fail. Consequently, if you have replaced an alternator before because of bad diodes, and the replacement fails for the same reason, there is likely a bad connection or open circuit between the alternator BAT (B+) terminal and the positive side of the battery circuit. Do a voltage drop test to check the entire circuit.

To do a voltage drop test, with the engine idling, touch one test lead of your voltmeter to the battery positive (+) post, and the other test lead to the BAT (B+) terminal on the alternator. Ideally, the voltmeter should read less than 0.2 volts.

If you see a voltage reading greater than 0.2 volts, it means there is excessive resistance somewhere in the circuit causing a voltage drop in the wiring circuit. Check all the wiring connections (use electronics cleaner to clean connections), and make sure the terminal connectors on the ends of the wires are clean and tight.

A negative side ground circuit test is made by touching one voltmeter test lead to the alternator housing, and the other test lead to the negative battery post (not the terminal clamp) with the engine running and charging system loaded. If good, the voltage drop should be 0.2 volts or less. If higher, inspect and clean all ground connections as needed. Also, check for broken, loose or missing ground straps between the engine and body.

Checking for voltage drops in a circuit is a good way to find hidden problems that may be causing a charging problem. Voltage drop tests must be done while the engine is idling with a charging load on the system. In other words, there must be voltage flowing through the circuit for the voltage drop test to detect a problem. Voltage always follows the path of least resistance, so if the connection being tested has too much resistance some of the voltage will flow through the voltmeter and create a small voltage reading.

In any event, an auto electrician will be aware of the tests and causes stated above so I would advise consulting one if you have the means to perform the tests and come up empty handed.

As far as your fuel pump issue is concerned, the ultimate decision as to which path you take is up to you. Weigh the costs of the OEM replacement with the aftermarket choice and if you're happy to go with the OEM, then take it.

If on the other hand you intend to modify your vehicle at a later date, your OEM pump will not be capable of supplying the required fuel needed and you'll be looking at an aftermarket pump regardless.

Like I said, what you do here is your choice.

[benro2]

Ah, thanks for all that, I'll definitely look into it!

Regarding the fuel pump, from what I can see, it's not an in-tank pump and is just behind the inner boot wall, underneath the rear strut brace?

Any ideas on how long it would take a workshop to swap? I've been quoted about $250 for a direct replacement (but not "performance") aftermarket pump... just hoping the labour won't be more than 1-2 hrs...