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Question about carb'ing a FI 140

jnvolvo

New member
Joined
May 19, 2019
Location
MN
FI system is acting up. Was planning on swapping to carbs. Was pondering potential issues with the rest of the fuel system? Will the pump and stuff from the FI system push fuel properly? I know the two have different pump setups, tanks, etc.

Just trying to get this on the road. Thanks.
 
Which fuel injection, D-jet with electric injectors or K-jet(CIS) with mechanical injectors?

And what is the problem problems?
 
You appear to be new here, so I have to ask about your automotive repair skill level?

I like to keep them fuel injected as they run better, but that can get expensive depending on what's wrong. And to properly diagnose K-jet, it's critical to have a proper fuel pressure gauge to check the system pressures.

Bottom line is, it can be fixed and it could be something simple like dirty injectors or it could be something more expensive.

As previously mentioned, you shouldn't try to use a high pressure fuel pump with a carb(s).

Low pressure electric fuel pumps are available or you could bolt on a mechanical fuel pump.

Have you decided on a carb(s)?
 
I have heard you can just use the intank pump and eliminate the high pressure pump, and an adjustable fuel pressure regulator to drop it to carb pressures. Should be no problem adapting an FI tank and sender to carbs. You are basically eliminating the high pressure pump and the return line should be blocked. Going the other way is the hard one. The FI cars need extra connectors for the fuel return and provisions for the intank pump that the factory carb cars do not have because it is unnecessary.
That being said, Double check every vacuum line. Many issues with these old cars relate to vacuum lines. Check all of them and replace any questionable ones. It is cheap and easy. I would never change or rebuild any FI parts on any car until I am sure the vacuum system is operating properly. A cheap hand vacuum pump from amazon can make finding leaks a breeze.
 
There is no in-tank pump on a D-Jet car, I'm not sure about a K-Jet, but I don't think there is. The main pump underneath the car just pulls the gas out of the tank on its own.

D-Jet is, in many ways, easier to work on that K-Jet. Since it is a more modern style system, just a bit simpler and using some iffy vintage parts (like the MAP sensor). It's easier to replace the old analog electronics with something modern like MS.

But K-Jet is a step back in terms of technology. More like the mechanical fuel injection systems of the 50's and 60's.
 
There is no in-tank pump on a D-Jet car, I'm not sure about a K-Jet, but I don't think there is. The main pump underneath the car just pulls the gas out of the tank on its own.

D-Jet is, in many ways, easier to work on that K-Jet. Since it is a more modern style system, just a bit simpler and using some iffy vintage parts (like the MAP sensor). It's easier to replace the old analog electronics with something modern like MS.

But K-Jet is a step back in terms of technology. More like the mechanical fuel injection systems of the 50's and 60's.


My k-jet turbo had an intank lift pump. I looked into all this stuff because it had been run on really bad gas with a bypassed fuel filter when I bought it and with new parts it would have been cheaper to get webers with manifold than k-jet parts. Fortunately I found a trashed turbo car to strip, and fixed my k-jet. Parts can be really pricey.
According to greenbook, pre77 cars sometimes came with lift pump and sometimes without. After 77 they all had a lift pump in the tank.

Go to this site: https://ozvolvo.org/archive/archive.php
and look for this file: TP30454-1_k-jet_ci_system_b19_b21_b23.pdf Page 57

Forgot to mention in last post, change all fuel filters. Intank sock included. Plugged filters will cause gradual degradation of performance.
 
NotSoFresh,
1974 140's are the only 140's with K-Jet, and they did not have an in-tank pump. If the K-jet is not working, it can be difficult to diagnose unless you know what you are doing.
I've only had one K-Jet Volvo, a 75 242. I hated it because I was young & didn't understand it.
To convert to carbs, you would need to remove the electric pump at the tank, plug the return line at the tank, and install a mechanical pump.
Steve
 
NotSoFresh,
1974 140's are the only 140's with K-Jet, and they did not have an in-tank pump. If the K-jet is not working, it can be difficult to diagnose unless you know what you are doing.
I've only had one K-Jet Volvo, a 75 242. I hated it because I was young & didn't understand it.
To convert to carbs, you would need to remove the electric pump at the tank, plug the return line at the tank, and install a mechanical pump.
Steve

I forgot we were talking 140, not 240. In my post I commented that 75-77 k-jet 240s frequently came with no lift pump. It makes sense that the 74 140 would come this way as well because you can use the same tank as came on all the previous cars.
 
You appear to be new here, so I have to ask about your automotive repair skill level?

I like to keep them fuel injected as they run better, but that can get expensive depending on what's wrong. And to properly diagnose K-jet, it's critical to have a proper fuel pressure gauge to check the system pressures.

Bottom line is, it can be fixed and it could be something simple like dirty injectors or it could be something more expensive.

As previously mentioned, you shouldn't try to use a high pressure fuel pump with a carb(s).

Low pressure electric fuel pumps are available or you could bolt on a mechanical fuel pump.

Have you decided on a carb(s)?

I come from a MK1 and MK2 VW background, so CIS is nothing new to me. But the info on volvos is pretty hard to find. I confirmed with redwood that my guess was correct that the carbed 140 would be like 3psi in the line vs the 65-70psi from a pump that feeds a CIS system. I had assumed that that was the case, thus my question just to verify from guys who know these cars details better than I do.

If I were to carb it I'd go with twin SU's. I like the simplicity, but at this point I'll spend some time diagnosing the KJet when I have time.

Thanks for all the assistance guys. 👍
 
I forgot we were talking 140, not 240. In my post I commented that 75-77 k-jet 240s frequently came with no lift pump. It makes sense that the 74 140 would come this way as well because you can use the same tank as came on all the previous cars.


Read before commenting and further confusing people

+1 and the tank changed in 74 just for good measure.
 
+1 and the tank changed in 74 just for good measure.
Miss 1 digit dammit....Didnt mean to misinform.....What I posted was perfect info for an early 240 cis car. My big mistake was after I was informed about the missing the 140 thing, I assumed the k-jet on a 74 140 would be similar to on a 75 240.
Either way, neither car had an intank before 77.
Here is a supplier for a pierburg mech pump to make up for it:
https://www.cvi-automotive.se/en/articles/2.20128.58615/fuel-pump-b19b21b23b200k-b230ak-pierburgbcd
fuel-pump-b19b21b23b200k-b230ak-pierburgbcd.jpeg
 
Spring of 1975 2 girls that were related to the Swedish Ambassador were on a see the USA trip. There car started dying every 100 miles or so when they got into hotter climate. They left the car and flew out. As you could imagine the phone lit up. Volvo told us to drive it like it’s yours. We made a 120 mile road trip and noticed the fuel pump making uneven noise but still ran. Reported this to DSM. Weeks past- car ran ok. DSM came in with a kit to add a pump inside the tank. Back then the float opening was small. Engineering figured out they were vapor locking. The flat rate on this update sucked. Another tale from the past
 
Well when we had a 74 kjet 142. The car started actiing up like shuddering when running, low on power, and in general being a bitch.

Turns out there is an intank sock around the fuel pickup pipe inside the tank. Those things clog up big time.

It is supposed to be replaced every so often and it can also be deleted if you want. Better to have some filtering. But at the time this happened there was no replacement part for the sock. It is located above the brass plug in the bottom of the tank. Once you remove the plug you can grab the sock and pull it out.
 
Well when we had a 74 kjet 142. The car started actiing up like shuddering when running, low on power, and in general being a bitch.

Turns out there is an intank sock around the fuel pickup pipe inside the tank. Those things clog up big time.

It is supposed to be replaced every so often and it can also be deleted if you want. Better to have some filtering. But at the time this happened there was no replacement part for the sock. It is located above the brass plug in the bottom of the tank. Once you remove the plug you can grab the sock and pull it out.

I'm thinking that could very well be the problem. She'll start and idle for a bit and you can drive it up onto a trailer or around the yard quick but then she sputters and dies.

One of the first planned steps is to yank the pump and get a look at it/the tank and check for any blockage between there and the front end.
 
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