Fuel pump

[Alex Wong1697456877]

My car seems to be struggling to maintain fuel pressure.

 

At idle and engine off, I get a steady 3bar (43psi)

If I prod the throttle, I get dips in fuel presure down to 35psi

I'm going to change the filter first, and maybe the regulator but from experience, the last time I had this problem, it was the fuel pump.

 

Caterham parts are out of stock and seem to only list the pump with the whole assembly with the bits that attacj=h it to the tank. They want £300 for this.

http://caterhamparts.co.uk/product.php?id_product=98

Would this do the job? - At <£100, and without all the extra bits I don't need, it looks much more temptimg

https://www.merlinmotorsport.co.uk/p/fuel-pump-caterham-injection-motorsport-ac-6443327-itp144?utm_source=Google&utm_medium=ShoppingUK&utm_campaign=ShoppingUK&vat=on&currency=GBP&gclid=CjwKEAjw-8ihBRD2t9qT3NaW7igSJAD3_sNV2pzl33x_rUk6mRUc4QldIR0OXf_Ni1tQLS-OmySppBoC21nw_wcB

 

From memory, when I last changed the fuel pump, it was listed as a "high pressure injection pump" rather than a standard in tank pump.

Is there anywhere else that I can source a suitable pump from?

The engines a Swindon JPE Vauxhall engine.

 

Thanks

[Alex Wong1697456877]

Any reason why I shouldn't get this :

http://www.jjcraceandrally.com/autograss/aps-range/automotive-plumbing-solutions-gss342-walbro-255-type-uprated-fuel-pump

 

or any other GSS342 pump?

 

[ECR]

Looks Ok to me Alex ...

I've mailed you all I have on replacement pumps.

I seem to recall that the connections need swapping round on some pumps to make them run in the right direction ...

[Alex Wong1697456877]

Thanks Roger. Got your mail.

daveK suggested swapping fuel filter then reg then pump. I'll do that.

The good news is that after cleaning up the plugs, it now revs cleanly. It's been up and down the lane and feels good. The Stack does flag up fuel pressure drops on poking the throttle so I'll try and sort that. Has your engine gone back in?

[ECR]

Yes, engine's back in (and a cover over the clutch lever !). I'm waiting for a DHL delivery from Nick Dinsmore before I run it. He's very kindly sent me his swirl pot to try at Dijon on the 23rd. I hope that it will get rid of the problem of header tank blow off. It seems to have worked for others (Paul Gibb, Mark Collins to name 2) so I'm optimistic.

I've just relocated my fuel gauge to in front of the gear lever (on the removable gear lever cover) as I couldn't see it with the alloy tonneau on.

You took the regulator apart I think, was that before or after the fuel pressure drops (you can see where I'm going with this ...)

 

[Pendennis]

The pump you list on merlin website is replacement for the high flow R500/JPE set up, I've fitted that one and measured the flow rate to be correct, but polarity of the wires must be reversed to make it pump in the correct rotation.

[Alex Wong1697456877]

Thanks for that Pendennis

 

Before I took the regulator apart, it was always running low. I took it apart, cleaned it up and reassembled, then got exactly 43psi which is what I sey it to many years ago. - but yest, that on it's own makes it likelt to be the culprit. It's just that the symptoms mirror my first fuel pump failure - except the pump doesn't sound sick like the last one did.

[Paul Deslandes]

Hi Roger

curious to know what the header tank blow off problem is.  I don't think I have it but would like to know what to look out for.  I always thought swirl pots were part of the fuel system!

Sorry for slight hijack Alex

Paul

[ECR]

Moving my header tank to a high point on the bulkead reduced the small but irritating spray from the header tank cap on hot days at power circuits. All was well till I upped the power, drove faster (:)) and did trackdays in a hot climate. I now get a warm leg where the blowoff trickles past the bulkead. As for an explanation, I,m sure that Nick won't mind me reprinting his comments.

Cooling system Nick Dinsmore

As discussed before, I had exactly the same problems with the expansion tank on my car. The Caterham-supplied tank has two faults - 1: It is mounted too low - ie below the water level at the top of the cylinder head and 2:It feeds into the (low pressure) inlet hose to the water pump, with a (high pressure) return pipe from the top of the head by the inlet manifold. While the system is almost OK on standard engines, it just doesn't work once the revs get above about 7500. The air in the expansion tank tries (and always succeeds, in my experience) to reach the highest point in the system, the cylinder head. The engine then starts to overheat (which often goes unnoticed as the water temperature sensor in the thermostat housing may read low as it is now surrounded by air rather than water). The thermostat is also in air for much of the time and so may be fooled into not opening properly. The expansion tank is now 100% full of water which gets blown out via the cap as the system overheats and the pressure rises. The low pressure feed/high pressure return to the expansion tank only aggravates this problem. Caterham started to fit a non-return valve in the return pipe to the tank in an attempt to control this cycle but, while this helped, it didn’t solve the problem as the fundamental cause is point 1 above. Fitting a lower temperature thermostat  is a good idea as this can help prevent everything overheating to the point where water is blown out. This may be OK for the road but go to a fast circuit (eg Spa or Goodwood) where 8000+ rpm are used for long periods and the problem reappears. Bleeding the system restores the air and water to their correct positions, but not for long!
Anyway, enough of the problems, and on to what can be done to correct this.
On my car I removed the plastic expansion tank and blanked off the inlet into the bottom hose. I then had an aluminium swirl pot made which is inserted in the top radiator hose. The return pipe from the head by the inlet manifold is also fed into the swirl pot. The swirl pot is now at the highest point in the system, which therefore becomes self-bleeding. I have used this system for four years and it never blows out any water at all and the water temp stays in the 80s even with 8500rpm circuit use on hot days.

 

[Paul Deslandes]

Thanks for the explanation Roger.  I don't think I've had this problem but perhaps have never put the car into a similar situation, other than possibly at Castle Coombe where it probably doesn't get as hot.

I'll be interested to hear how the test at Dijon goes.

End of highjack (for now at least).

Paul

[Mick Day]

This header tank also works well with a K series, especially with a dry sump oil tank in front of the engine.

[TomB]

Ive picked the latest thread on fuel pumps to query the model I need from Merlin Motorsport.  

Im looking to replace my tired pump from my 1996 K series, as the engine is now bigger and the fuel pump is old in a quest to find my missing horses.  

Merlin stock the uprated Caterham pump, ITP144 https://www.merlinmotorsport.co.uk/p/fuel-pump-for-caterham-7-motorsport-upgrade-pump-itp144

However, looking in the archives also suggests their ITP101 for a Land/ Range Rover is also appropriate https://www.merlinmotorsport.co.uk/p/fuel-pump-landrover-lse-4-2-6443228-itp101

Based on the pictures on their website, they appear to have different fittings/ connectors.  Can anyone confirm which is the right one for a 1990s K series car?  

Thanks, Tom 

[TomB]

Ive now got mine stripped, part number is 6443327, with A1244-1 also marked.  There seem to be a range of possible replacements, including the two from Merlin above, a Wallbro kit and some others.  These all seem to have a plug in connector on the pump and short length of cable, whereas the existing pump I have simply has two spade connectors (one ~5mm, one 3mm) connected to a couple of inch long wires.   

The electrical connector for the pump cradle is soldered from the outside and contained within an epoxy glue filled housing.  Then inside are the short wires with spade connectors to the pump.  

Id appreciate others experience of what they had to do to get new pumps to fit to older cradles.