More stuttering under load -suspect fuel pump

[TheScAtMaN]

Hi guys

I have a very similar problem to Nick H where my car becomes stuttery and hesitant under load:
http://deloreans.co.uk/forum/showthread.php?tid=5821

But in my case I strongly suspect it's my fuel pump. A couple of months back I took my car down to Alex Canini near Hastings for a tune up and suspension work.
He discovered that my fuel pump would change output depending on what angle it was placed in!
It's not something I had noticed before but now that my car is much more stable handling wise and after tuning I find myself driving her faster.


Our working theory is that under heavy load the pump is shifting slightly and cutting out, as the car slows and it moves back normal flow is returned resulting in the pulling feeling I get.

The previous owner had replaced the pump about 3 years ago but seems it's a bit of a noddy-no-make. Assuming it is the pump what's the best one to replace it with?
I know there is an all in one jobby with the filter built in from the likes of Special T or should I go with the more traditional one sold by DeLorean Go?

[Rissy]

From other people i've heard having difficulties with the new all in one style, i think i'd stick to the more traditional type myself.

Sourcing is up to each to make their own decisions, but i'd be inclined to go for something like this from our old friends at Opie:

https://www.ebay.co.uk/itm/Bosch-Electri...Sw-1xZebet

[Chris Williams]

I think all have issues, the new 'all in one type' are having issues. Apparently some people are not happy with the one that SpecialT supply (though had no issues myself) I do wonder if the OE set up as Chris suggests is the way to go.
Chris

[Nick H]

(02 Aug 2018, 19:54)Chris Williams Wrote: I think all have issues, the new 'all in one type' are having issues. Apparently some people are not happy with the one that SpecialT supply (though had no issues myself) I do wonder if the OE set up as Chris suggests is the way to go.
Chris

It looks like the Special T unit is based on this https://carter.opticatonline.com/part/bc...er-p74905m

Not sure what John does to modify them to increase fuel pressure. As according to the specs it’s max working pressure is 60psi. A Bosch CIS K jet pump is about 80psi. 
Check out this video of a chap installing the carter pump. Note in passing at the end of the video he mentions the car has a hot start issue.
https://youtu.be/4-PzygwpVkE

My Special T pump appears to run fine, it’s not noisy and the filters are clear. But it’s definitely not producing enough pressure. I suspect a bad tank of fuel but it could also be the fuel injector cleaner I tried. So I have reverted back to my original Bosch 957 that has been in the car since I bought it nearly 20 years ago. 


Nick H

[Nick H]

Well just to update everyone. I took the car for a long test drive today. 
 It was probably a good day to do this as Peterborough is more like L.A. Temperature wise today  .

First drove to my local Tesco and filled up with Momentum 99. Which as far as I can find, from a bit of surfing the net. Has very low or nil ethanol level.

Car re started perfectly. I then took it for a 50+ mile drive. Aircon on max, fan speed 3 or 4 for the whole drive. I did a range of motorway, backroads and city start/stop driving. I wanted to get the fuel really hot in the tank. As when I had the original fuel pump set up in the past the car would sometimes act like it was running on kangaroo juice if it got hot and the pickup hose would collapse. 
Had no problems with that today. Pickup now has a spring inside it.

The car is transformed performance wise. It should be really as it’s running a near completely new injection system. I suspect that 6 new injectors and a cpr have made the most difference. Along with returning to the original fuel pump.

I did some spirited driving and it was getting to the point that it would need better brakes so at that point I stopped being silly.  
Had absolutely no stuttering under load.

Nick H

[TheScAtMaN]

Glad to hear you are all sorted now Nick!
I'm going to go ahead and order a new pump, probably from DeLorean Go. I probably could find an equivalent from a different vendor a bit cheaper but if I have any problems it will be easier to return.
I will replace the filter while I'm in there and I know the fuel pickup line already has the strengthening spring fitted. Anything else I should be looking to replace?

My biggest problem is that my tank is 2 thirds full at the moment. Perhaps I need to drive round the block a few dozen times!

[Nick H]

(04 Aug 2018, 18:39)TheScAtMaN Wrote: Glad to hear you are all sorted now Nick!
I'm going to go ahead and order a new pump, probably from DeLorean Go. I probably could find an equivalent from a different vendor a bit cheaper but if I have any problems it will be easier to return.
I will replace the filter while I'm in there and I know the fuel pickup line already has the strengthening spring fitted. Anything else I should be looking to replace?

My biggest problem is that my tank is 2 thirds full at the moment. Perhaps I need to drive round the block a few dozen times!

Well pleased to finally have the problem sorted.

DeLorean Go are a very good vendor in my experience. You can get genuine Bosch
Pumps from other sources but you’re looking at over £100. 

I may be worth checking the front frame earth point and clean or replace hardware.
Use a bit of conductive grease. Check the fuel pump boot has not started to degrade.
I had to replace mine.

As for removing fuel I disconnected the fuel supply line (inner most connector as you look
at it from the front of the car.) I then placed the hose in a fuel can and removed the rpm relay.
Then you can set up a wire with two spade connectors and a switch. Look up
Jumper rpm relay on the web and connect the two spades to the appropriate terminals.
Then you can use the fuel pump to empty the tank into fuel cans. 
Obviously take appropriate safety precautions. And you do this at your own risk.

The option I used in the past is a fuel siphon. You can pick these up cheaply, it’s just a hose 
with a primer bulb built in that you squeeze to get the fuel flowing. Normally 
they only last for one use as the fuel attacks the plastic but you’ll have no problem 
emptying the tank. Obviously first thing with this method is to disconnect the battery from
the car.

Regards 
Nick H

[Chris Williams]

Quote:My biggest problem is that my tank is 2 thirds full at the moment

My tank has space if your looking for somewhere to transfer it to....

[Nick H]

(04 Aug 2018, 21:19)Chris Williams Wrote:

Quote:My biggest problem is that my tank is 2 thirds full at the moment

My tank has space if your looking for somewhere to transfer it to....

[TheScAtMaN]

Thanks for the offer Chris, very generous of you!

Actually, in all seriousness, do you have a large fuel can I can borrow (and maybe a pump) ;-)

[Chris Williams]

Quote:Thanks for the offer Chris, very generous of you!

Actually, in all seriousness, do you have a large fuel can I can borrow (and maybe a pump) ;-)

Yep I'm like that.......... I have a 20l jerry can you can borrow if it helps and some 10l plastic fuel cans.

[TheScAtMaN]

Ooh, yes please!