Fuel pressure drop

Good day everyone i have a Z11 1991 n/a

She has 90k on her and in south Africa we don’t have many of these cars running so there is almost bo information available

Car needs a bit of love and im really struggling with parts and information
Many many thanks to joe with his videos
The first issue i would like to tackle is the fuel pressure drops after shutting the car down im assuming fuel pressure regulator, and does puff a bit of vlaxk smok if you rev it hard (higher rpm)

Best regards

Out of curiosity, why do you assume it is the regulator?
Couldn’t it could be anything on the fuel rail? Leaking injectors, fuel pump, regulator or fuel line leak.

True that was just an assumption
I’ll check the system for leaks
May i ask how fuel pump could play a role?
Is there a check valve on it ?
Thanks Joe for your reply

I thought that there was but I am hoping that someone else on here can confirm it.

If fuel pump doesn’t have a proper seal (it bad oring) it could cause bleed off of pressure.

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Maybe fit an external fuel pressure guage to see what the pressure is exactly doing

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Hi ihad the same issue , long story short i fitted fuel pressure gauge so i could see pressure when car was running . ended up needing new fuel pump . i have full workshop manuel if you need it . but i am sure its on here . PM me if you cant find it or drop me a email " [email protected] "



Good day again
I have the workshop manual and planning to fit a fuel pressure gauge to be able to figure out what is happening.
The car developed a new issue, If the engine is warm specifically going through traffic for a short time if you floor it the engine surge’s around 3 to 4.5k rpm
To me feels like fuel starvation since as soon as i release the throttle the engine runs again
However at the same time if i throttle it a slowly (not flooring )
The engine rpm will keep raising beyond the surge

What about doing fuel pump hot wire if yours is twin turbo like mine . i have wired my fuel pump to realy etc to batt cable . 3SX has mod for this

Mine is not tt unfortunately

Can someone educate me please.
These cars have run fine without any fuel mods for 30 years. Why do we suddenly need one?
If there is a fault, why not fix it rather then cover it up with a mod?
I thought the purpose of the resistor is to prevent the pump working harder than it needs to on idle etc.

The surging is another indication that the fuel pump may be failing.

I agree with keeping the car all original
And that is my plan with the car
Can anyone help with part number for the fuel pump?

@Joe90 i do get it but as time passes its harder and harder to find the parts to fix . i only did the mod { fitted realy as the car would not start no fuel pressure and i needed it to go a was moving house . my plan is to fix back to how it should be . it was just to help Keyven figure out what the problem was . as if you get 12 volt to pump get some good pressure . that might help him . i think the issue with my car is the pump resistor pack thing which i am going to look at next.

@Joe90 do you know the part number or a compatible fuel pump i can use?
Im also shit scared to break the line

I don’t know the part number but you can get it from mitsubishi or another parts seller. If you have the na engine, the pumps are readily available from a hundred different sellers on ebay, they are very cheap and identical to the original pump. I do not have them on my website because they are so easy to get hold of from retail sellers. I do have replacement rubber section of hose if you need to cut it and sometimes this is the safer option if your metal line is looking a bit fragile.
You will not break the lines if you follow my video and take your time.

I just had a quick look on ebay. What a frightening place to get parts for our cars if you don’t know what you are looking for. It seems that they are all using the words ‘fits 3000gt’ but it’s a very liberal use of words. Most of them come with a bag of adapters and hoses to make it fit but it is not a standard pump. Maybe someone on here can recommend a seller that they know has the correct pump. If not, I will sort you out but you will have to pay more through me because I don’t bother buying these in bulk for discount price. Maybe I will get some for my website after all. You could also try evil empire.

Thanks alot for your help.
Ill take of the pump and if i cant find it in south Africa ill definitely contact you

@Joe90 @stealthee @gto-power @Supertec
Thanks to joe i managed to remove the fuel pump without any damage however what i see inside is very confusing
1-fuel is quite contaminated
2 - take a look at this pump i cannot figure out why they have done this

This is probably because the car has been standing for a while with low grade fuel or in damp conditions without keeping the tank full. I would flush the tank and fit a new fuel pump. See what it comes up like. If it is still bad looking inside, there are treatments available.
That is not the correct pump and does not appear to fit properly. This may be the cause of the fuel pressure drop.