People’s thoughts on fuel pumps and rubber hose repairs rather than replacing

I might need a new fuel pump, and the prices range from £150 to £700. Is this a part that you shouldn’t scimp on, and the old adage applies buy cheap buy twice. My car is a 1999 996.1 C4 RHD which seems to be the most expensive variant for pumps due to the saddle bag petrol tank.

Baron, what makes you think you need a fuel pump..?

All the symptoms I’ve checked, humming whine from around petrol filler wheel arch, issues starting when very hot, I’ve gone through the codes on my Icarsoft and looked at live data etc, have been chasing this issue for a while, new MAF, new everything to be honest. Everything is just pointing the fuel pump I’m going to do a final check this week and do a test on the fuel pressure, this should confirm

Hmmm, in my experience of fuel pumps, one get's what one pays for.... there was a thread on here some time ago discussing Bosch pumps that are made in the same factory but on different lines for various car maker brands and there was a general feeling that there were differences in quality so i'd advise not to buy cheap as you'll probably end up buying twice, an experience i had with a Corvette some years ago.... oem was in the end the best option and i;ll guess porsche is the same. Hope you get it sorted Baron.

i've got two fuel lab pumps down inside each saddle. i would just avoid any cheap chinese/ebay stuff and get the correct branded stuff from approved sellers - i always check the manufacturer websites these days for approved retailers. OEM should be fine if not pushing any big HP. however you might get a more modern quiet pump with a lower current draw that will fit in the basket - i think someone fitted a walboro on 6 speed

No option on an early C4 pump Im afraid, Porsche exchange only £454+

Nearly £700 on D911.

Mine went on mine last year and they ain’t cheap…..from memory £600-700 but if it lasts as long as the first one that in theory softens the blow. And on mine it gave no issues until it was too late

It’s a bit of hit for sure, I’ll do the pressure test next week and hope it’s all good but everything is pointing to the fuel pump, I think Porsche do an exchange for around £400 so I’ll investigate that option if it is the pump.

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Porsche exchange only £454+

I e watched a couple of videos, in particular this one, and it seems that the common failure point is not the pump but he plastic hoses that are part of the pump, the new pumps have changed that design. The video is for the turbo but I’m led to believe it’s a similar fuel pump to accommodate the AWD Has anyone tried to change the two rubber pipes, which is going to be pence as apposed to hundreds?

I would have a go at replacing the rubber pipes, mine is ok a the moment but this looks like a failure waiting to happen, i may have a look over the winter as a precautionary job.

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Ouch

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If you replace the hose, then just be aware that it isn't just normal fuel hose. There's a submersible hose you need to use, that is specific for the job. £1.20 per cm. Buy Gates Submersible In-Tank Fuel Injection Hose 10mm I.D. per 10cm GAT27097 from Competition Supplies - Worldwide Shipping Available

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Do you know if this is the correct internal and external dimension?

This makes sense as to why they are now exchange

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I don't know the exact dimension. When we built up my fuel system, there was a shortage of this stuff so we had to wait, also remember it being very expensive!

Fuel pump (assembly) is checked by pressure at the fuel rail (there is a schrader valve to connect a gauge to measure) and amount delivered through the return line in a certain amount of time at the tank. Any whining,groaning and hissing noises point to vent valves not working correctly or hoses pinched/blocked.

Update: I got the pump out, not a bad job. I’ve inspected all the hoses, they all look good, so it’s going to be a new pump from Porsche I did look at replacing just the metal motor but that is a whole other world of correct sizing flow rates etc, so I think I have no option. But if others have a similar it’s definitely worth investigating g the hoses first as this is a simple cheap fix and is the week point in most cases.

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Yes I had it preassure tested and it was all good about a year ago, however it only get an issue under certain circumstances ie in traffic when the fans come on, it then has this issue. Ive run diagnostics and everything has been changed except the fuel pump. It’s all pointing to that, and as I’ve got it out it’s done 205k miles and it 27 years old it won’t do any harm to swap out now it’s already out To add I replaced he tank vent valve in 2022 and have checked all other associate lines for blockage or snagging etc.

If the fans come on and then you notice something about the fuel pump, it points to a drop in voltage supplied to the pump due to the power drawn by the fans. That could be due to high resistance in electrical connections (oxidised contacts), bad grounds etc. Worn brushes inside the pump's motor can be expected at 205k miles and increase the current drawn, thereby dropping the voltage, so replacing it is a good idea. Have look at its connections too to get the best out of the new motor.

New fuel pump from Swindon OPC fitted cost £480 inc vat and exchange pump. Taken for a couple of spirited runs to get hot to try and replicate previous issues, all good so far, no noise/whine from the front as before so fingers crossed this has finally solved a very long standing issue of occasional hot start and rough idling problems. Interestingly I never once had a check engine light, I only found the codes by plugging in my iCarSoft reader.

For anyone wanting to do this themselves, the original video I posted is great but it’s for a turbo and has slightly different connections on he back of the pump, this video is great from an instructional point of view but he below video is for the actual C4 hen this gives another perspective.