hot starting issue

mike1978 · Posted: Thu Jun 12, 2008 7:37 am Post subject: hot starting issue

now i`ve finally got everything running i`m starting to try and fix some of the teething problems.

One of them is that when the engine is hot and been sat for say 15/20mins, the engine struggles a bit on starting. I can turn it over for about 5 seconds and then it will catch a bit then the engine will fire and idle normally - it drives fine after this.

I thought it might be some sort of fuel evaporation perhaps? Has anyone else experienced this? Should the fuel pump be pressurised as when i take the hose off between the pump and engine, the fuel doesn`t fly out or anything when i remove it.

Cheers,
Mike

bruine bus · Wannabe Joined: 19 Apr 2008 Posts: 7

Hi Mike,

I have been following your threads and problems and see a similar pattern with my conversion. How is your fuel pump? My new one sounds like somebody threw in some marbles and although it still works at the moment it is clearly indicated it is going to die soon! I just have a feeling that these pumps are not up to their task so I am going to buy a new fuel pump which is hopefully of better quality.

Cheers,

Berry

ElusiveStranger · Posted: Sat Jun 14, 2008 5:25 pm Post subject:

Mike,

I think Bruine's right

When you first turn on the ign: alt & oil lights on but not to 'start' posn do you hear the pump prime? They should run for approx 1 second then stop

The lines aren't pressurised before the pump, they're fed by gravity, mine's under the tank. Where's yours?
After the pump is another matter. I removed a line hours after priming and fuel squirted everywhere. Always wrap a rag around the line if removing. Pressure should stay in those lines for a while. There's generally a non-return valve in the pump.

Try key on so lights come on & pump primes. Turn off, repeat, turn off, repeat a few times when you know it prolly won't want to start. Then go for a start. See what happens

The way a pressure regulator (Scooby style) works is...
Basically it gets to pressure on idle & returns excess fuel to the tank. When you put your foot down it increases the vacuum to the regulator (pipe from inlet manifold to reg). This closes down the through flow to increase pressure in the lines.
This means that more fuel is injected into the cylinder for the same opening time on the injector. The ECU also controls the duration.
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'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
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doppelganger · Posted: Sun Jun 15, 2008 8:16 pm Post subject:

ive removed a fuel line after 6 months and been sprayed in the face Laugh Out Loud

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ElusiveStranger · Posted: Sun Jun 15, 2008 8:21 pm Post subject:

hehe, hope it didn't get you in the eye fella.

Mine's never sat for 6 months!

I think the reason it starts from cold would be...
when hot there's vapor in the hot FI lines after 20 mins standing.
When the engine cools the vapor creates a vacuum and nature abhors a vacuum and replaces it with petrol, sucking through the pump.
_________________
The advice you receive on here is worth the paper it's written on.
Your experiences are worth shed loads to others, including the f'ups - live and learn.
Wouldn't YOU rather learn by someone else's mistakes? So would they.

'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
I don't lean forward for hills any more Grin

Bugger, missed out on "Live fast, die young"

mike1978 · Posted: Mon Jun 16, 2008 12:40 pm Post subject:

thanks for the info - for some reason i haven`t been getting emails when this thread is updated.

when i swithc on the ignition i can hear the pump prime for about 1-2seconds so i think that is ok. I have removed the fuel line coming from the pump to the engine and there defintely isn`t any pressure there even a few seconds after having had the engine running - more like a dribble.

its a bit of a catch 22 situation, because i can buy a new pump off ebay and it might fix the problem but it also might not and once used i can`t really send it back.

here`s the one fitted for reference -

http://cgi.ebay.co.uk/NEW-V8-EFI-Type-Bosch-Fuel-Pump-ROVER-JAG-TVR-MGB-etc_W0QQitemZ110231672552QQihZ001QQcategoryZ10414QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

ElusiveStranger · Posted: Mon Jun 16, 2008 2:10 pm Post subject:

mike1978 · Posted: Mon Jun 16, 2008 4:08 pm Post subject:

haven`t tried the keying on a few times - when i get home tonight i`ll try after leaving it for 15mins or so. the pump is in the engine bay so higher than the tank - i have the fuel pipe leave the tank from below, then it gradually rises up and above the tank height, into the engine bay where it meets the fuel pump, then a filter, then the engine.

i`d rather not know about you feeling your fuel pipes to see if they`re firm!

mike1978 · Posted: Mon Jun 16, 2008 4:15 pm Post subject:

just looking at the fuel pump on ebay that i bought and it says rated at 36.25psi so if the regulator runs at 40psi static then my pump may not be to the job perhaps..

ElusiveStranger · Posted: Mon Jun 16, 2008 5:06 pm Post subject:

Right I'm at home.
I think the pump you have is the same as mine. Mine came off some sort of Jag (it was in the high pressure FI pumps box at the breakers)

My lines are hard, just squashable with thumb and fingers. That's over 24 hrs after use. I keyed on and they're hard, oooerrr.

The Scooby pump is rated at >65l (14.5 imp gals) / hr at 43.5psi
The regulator regulates to 43.4 psi

Edit:
The regulator with the vacuum pipe disconnected 41-46psi
The regulator with the vacuum pipe connected 30-34psi
End of edit

I think you should try lowering your pump though. I don't think they're designed to lift.
Hopefully DG or RJ will tell you if yours is in a bad position
_________________
The advice you receive on here is worth the paper it's written on.
Your experiences are worth shed loads to others, including the f'ups - live and learn.
Wouldn't YOU rather learn by someone else's mistakes? So would they.

'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
I don't lean forward for hills any more Grin

Bugger, missed out on "Live fast, die young"

mike1978 · Posted: Mon Jun 16, 2008 8:17 pm Post subject:

well, 3 hours after switching the engine off, i squished my fuel pipes and they`re very soft, under no pressure at all....

ElusiveStranger · Posted: Mon Jun 16, 2008 8:56 pm Post subject:

Pressure it up, clamp the fuel line after the pump near (before or after the filter), you might ruin the hose but it's cheap.
Return to it in tomorrow. If the hose is soft before the clamp - pump one way valve. I don't know if you can get a bolt on non return valve.
Soft after the clamp - regulator (or maybe injector but it doesn't sound like that!)
_________________
The advice you receive on here is worth the paper it's written on.
Your experiences are worth shed loads to others, including the f'ups - live and learn.
Wouldn't YOU rather learn by someone else's mistakes? So would they.

'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
I don't lean forward for hills any more Grin

Bugger, missed out on "Live fast, die young"