89 SK with carb conversion pump question

1287 Views 17 Replies 5 Participants Last post by 2013GV, 10 d ago

89KickIt

Discussion Starter · 3 mo ago (Edited)

My '89 SK that originally had TBI has a Weber carb conversion and I've found that the fuel pressure is too high at about 6+ PSI. I have a Redline 32/36 rebuild kit that I haven't put in yet as it specifies 3 PSI max for pressure.

The previous owner didn't know what kind of pump/regulator setup it had so today I dropped the tank and traced the fuel lines. I did not find any kind of regulator and there is no inline pump installed. It has the original return line in use.

So the next step is to pull the pump to see what kind it is. A new seal doesn't seem to be available at this time so I'm holding up for now.

Is it possible there's a low pressure, in-tank pump? What would you say these red stripes mean on the pump output fitting:

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turboguzzi

· #2 · 3 mo ago

still navigating blindly wihtout looking at your parts list?

😇

that thing on the center of your pic IS your fuel paump.... meant for EFI, so no wonder your weber cant cope with the pressure

United States, Vitara / Sidekick, SE416 (E03,E33:MY 1989), Fuel, 28 - FUEL PUMP - Catcar.info

2013GV

· #3 · 3 mo ago

I'm surprised its at 6 psi, have they got a return line at the Webber? A T connection i mean, fuel in and excess back to tank? If they have, fit an inline regulator under the hood somewhere.

fmartin_gila

· #4 · 3 mo ago

Search for 9710 Mr Gasket fuel pressure regulator. Amazon has it or any FLAPS (Friendly Local Parts Store) should have or be able to get for you.

Fred

Reactions: 1

89KickIt

Discussion Starter · #5 · 3 mo ago

turboguzzi said:
still navigating blindly wihtout looking at your parts list? 😇

that thing on the center of your pic IS your fuel paump.... meant for EFI, so no wonder your weber cant cope with the pressure

Umm...no I'm not flying blind as I'm quite familiar with EFI. Of course I know that is the pump. And if it's the original TBI pump (that runs at 37 PSI) I'm wondering how it's only 6 PSI at the carb without a regulator. I stated that the setup has the original return line in use and the pump is not deadheaded.

89KickIt

Discussion Starter · #6 · 3 mo ago

2013GV said:
I'm surprised its at 6 psi, have they got a return line at the Webber? A T connection i mean, fuel in and excess back to tank? If they have, fit an inline regulator under the hood somewhere.

Yes, as I stated....it has a return line. And I am 'surprised' too with no regulator in sight that it's at 6 PSI. I wouldn't think that a 'T' and a return line by itself would decrease the pressure down that far.

Therefore, I'm wondering if it is indeed the original TBI pump or they've somehow fitted either a lower pressure pump in the tank....or a regulator.

I can see that my SK is far from the ordinary, so maybe I should ask for replies only from members who actually have experience with a TBI vehicle that has been converted to carb.

89KickIt

Discussion Starter · #7 · 3 mo ago (Edited)

fmartin_gila said:
Search for 9710 Mr Gasket fuel pressure regulator. Amazon has it or any FLAPS (Friendly Local Parts Store) should have or be able to get for you.

Yes, I know I can add a regulator but the ones with low output pressures seem to be for mechanical pumps.

I've been checking for maximum input pressure specs because stepping down from 37 PSI to 3 PSI with reliability and accuracy is a lot to ask of a regulator. Wouldn't you think? Maybe that isn't an issue but I need to do some more checking.

I guess that since whatever pump it has now is down to 6 PSI, then adding a regulator would be the simple way to go. I'm just trying to find out what the setup is now in case I have to mess with it further. I travel a lot each summer and I carry along a spare fuel pump in whatever I'm driving.

turboguzzi

· #8 · 3 mo ago

ok, good, sounded from your first post that you didnt know if it was the std. pump, glad you do!

fordem

· #9 · 3 mo ago

89KickIt said:
I'm just trying to find out what the setup is now in case I have to mess with it further.

Dead head the pump in to a pressure gauge - see how high the pressure goes > 40 psi it's a fuel injection pump.

Whilst I strongly suspect that is the original pump, low pressure in tank swimmer pumps for carbureted engines do exist.

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89KickIt

Discussion Starter · #10 · 3 mo ago

turboguzzi said:
ok, good, sounded from your first post that you didnt know if it was the std. pump, glad you do!

Well, I don't know if it's the standard pump yet since I haven't pulled it. Externally it looks like the standard pump but since it's only 6 PSI (without a regulator) then it may be something different. And, it may be that the red stripes on the pump outlet signifies something? Not to owners of standard vehicles of course.

89KickIt

Discussion Starter · #11 · 3 mo ago

fordem said:
Whilst I strongly suspect that is the original pump, low pressure in tank swimmer pumps for carbureted engines do exist.

Thank you..that's what I suspected. I'll be checking the full output today.

2013GV

· #12 · 3 mo ago

89KickIt said:
Yes, as I stated....it has a return line. And I am 'surprised' too with no regulator in sight that it's at 6 PSI. I wouldn't think that a 'T' and a return line by itself would decrease the pressure down that far.

Therefore, I'm wondering if it is indeed the original TBI pump or they've somehow fitted either a lower pressure pump in the tank....or a regulator.

I can see that my SK is far from the ordinary, so maybe I should ask for replies only from members who actually have experience with a TBI vehicle that has been converted to carb.

Yes it would, in fact that's quite normal as the return only gets the excess from the regulator in the injection setup. It bet it will be the original tbi pump, block the fuel outlet line at the pump and I bet you go well north of 60 to 70 psi.

turboguzzi

· #13 · 3 mo ago

2013GV said:
Yes it would, in fact that's quite normal as the return only gets the excess from the regulator in the injection setup. It bet it will be the original tbi pump, block the fuel outlet line at the pump and I bet you go well north of 60 to 70 psi.

+1

fmartin_gila

· #14 · 3 mo ago

Food for thought - Is it possible (I don't really have any way to know) that the same fuel tank is used in both carbed & FI vehicles and that only the pump is different. In this scenario, would it be possible that the pump has been replaces by a low pressure pump. It is clear that the area has been visited before by the aftermarket clamp on the return line and the 'witness marks' (the 2 red lines) that a mechanic has put on the pressure side line.

Fred

fordem

· #15 · 3 mo ago

No - the carbed versions run a mechanical fuel pump driven off of the camshaft.

2013GV

· #16 · 3 mo ago

fmartin_gila said:
Food for thought - Is it possible (I don't really have any way to know) that the same fuel tank is used in both carbed & FI vehicles and that only the pump is different. In this scenario, would it be possible that the pump has been replaces by a low pressure pump. It is clear that the area has been visited before by the aftermarket clamp on the return line and the 'witness marks' (the 2 red lines) that a mechanic has put on the pressure side line.

Fred

I regularly mark connections once completed to confirm they are done to avoid missing one.

Reactions: 1

89KickIt

Discussion Starter · #17 · 10 d ago (Edited)

2

An update:

Finally got this figured out. You guys were right, it did still have the original pump and it put out 60 PSI. I see now that simply having a return line will drop the pressure at the carb down a lot. The old pump took a crap when I checked the pressure, even though it was only energized just long enough to get a reading on my gauge (about 2 secs). But then it was 34 years old...

So I shopped for a low-pressure inline pump and settled on a HEP-02A universal item that's rated at 2.5-4 PSI. These are really cheap on Amazon at $11 and seem to have hit-or-miss reliability, so I bought two.

The installation was made a lot easier by using parts off a 'sending unit' that's available on eBay for $40. These are basic in-tank modules that are minus the pump and strainer. The main thing needed was the 14mm female swivel fitting that I cut off and threaded onto the hard fuel line.

It also included a new seal plus a pigtail with an OEM-type connector that plugs into the harness. Easy-peasy. For wiring to the pump I used an XT30 connector which will make it easier to disconnect if I ever need to swap out the pump.

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2013GV

· #18 · 10 d ago

Glad you got it all sorted.
Hopefully you have many years of enjoyment, but, carry the other one (and tools) as a spare so you can change it when it invariably fails 4,000 mikes from nowhere.

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