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77 245 Sputtering/Lopping

MasterPratt

New member
Joined
Jan 16, 2020
I just recently bought a 77 Volvo 245 with the b21f (?) And the m46. She has a hard time running at lower rpms and higher rpms. It sounds cammed at idle but I went through and checked for vacuum leaks but couldn't find any. I'm not super familiar with Volvo's in general so any pointers would be greatly appreciated.
 
Even if there is no problem with the system. A fuel pressure check of the kjet fuel system would be prudent. But first take care of the basics with a full service including all filters and fluids.
 
Don't assume anything. I've had a bit of rough running when a couple of the valves needed to be adjusted. (for example). My favorite suggestion on an unknown vehicle is to be sure you have a functioning coil/amplifier module, and your spark wires are in good shape. The combination of weak amplifier/coil along with leaking wires can certainly cause roughness. Look at your plugs!
-L
 
Well we went through and found the fuel pressure was a bit low and the tank pump started whining so I went ahead and swapped that out with a new one. It helped improve things a little bit. I noticed as we would drive around the fuel pump relay shuts off when it back fires. I swapped the coil, the plugs, and the wires and I'm stumped on where to go next. We are getting around 70 psi for fuel pressure and we are set at 15? for timing. The car seems to really like 33? but I don't like it being that high. Unfortunately the link to the kjet troubleshooting doesn't seem to work any further help would be appreciated.
 
Does your car have the single fuel pump relay setup? There is a feed called 31b on the fuel pump relay that comes from the coil. Usually a white or white/red wire. If that connection is bad you'll get random cutoff.

The other thing to check is if you have the dual relay setup for the fuel pump. There is a connector on the side of the air flow sensor. For when the plate is closed. If that is randomly shorting out it can cut off the pumps.
 
Can't figure this thing out still... She runs fine with the cold start injector but the second it cuts off it runs horribly. Changed the fuel pumps and relays checked the lines for restrictions. I just need a list or something to use to trouble shoot with. I looked through the thread by TestPoint and I still can't figure it out... Injectors, plugs, wires, distributor cap, fuel filters, and coil is all new.... I hate just randomly buying parts hoping it'll work it's against what I'm about the next step is to take everything apart, clean it and put it back together or start trying to figure out how to install the megasquirt system.
 
Can't figure this thing out still... She runs fine with the cold start injector but the second it cuts off it runs horribly. Changed the fuel pumps and relays checked the lines for restrictions. I just need a list or something to use to trouble shoot with. I looked through the thread by TestPoint and I still can't figure it out... Injectors, plugs, wires, distributor cap, fuel filters, and coil is all new.... I hate just randomly buying parts hoping it'll work it's against what I'm about the next step is to take everything apart, clean it and put it back together or start trying to figure out how to install the megasquirt system.

It's possible.......especially since it has been back firing........that the big rubber bellow (air duct) that connects the throttle valve to the intake manifold has become dislodged (blown loose) and is a allowing air to bypass the throttle valve and leak uncontrolled into the intake manifold.
This will cause most of the symptoms that you are describing.
Run your finger around the edge of the black rubber bellow (located between the throttle valve and intake manifold) and see if it has become disconnected. Each end of it slips over a metal shoulder on each part and is held in place on each end with a big hose clamp and should be firmly attached.
It's worth a look.
Check it with the engine off and cold.

Hope this helps
Steve
 
Can't figure this thing out still... She runs fine with the cold start injector but the second it cuts off it runs horribly. Changed the fuel pumps and relays checked the lines for restrictions. I just need a list or something to use to trouble shoot with. I looked through the thread by TestPoint and I still can't figure it out... Injectors, plugs, wires, distributor cap, fuel filters, and coil is all new.... I hate just randomly buying parts hoping it'll work it's against what I'm about the next step is to take everything apart, clean it and put it back together or start trying to figure out how to install the megasquirt system.

it's possible.......especially since it has been back firing........that the big rubber bellow (air duct) that connects the throttle valve to the intake manifold has become dislodged (blown loose) and is a allowing air to bypass the throttle valve and leak uncontrolled into the intake manifold.
This will cause most of the symptoms that you are describing.
Run your finger around the edge of the black rubber bellow (located between the throttle valve and intake manifold) and see if it has become disconnected. Each end of it slips over a metal shoulder on each part and is held in place with a big hose clamp and should be firmly attached.
It's worth a look.
Check it with the engine off and cold.

Hope this helps
Steve
 
When you check fuel system pressure did you check control pressure? That is extremely important as it directly controls the fuel mixture from cold to a fully warmed up engine. If you have a clogged control pressure regulator that will lean out the engine both when cold and hot. This happens because the control pressure is too high which is what leans the engine out.

I'd also suggest making sure the timing belt is aligned properly. A belt off even one tooth can make the engine run like crap.

In the green books archive over on ozvolvo there should be a kjet troubleshooting guide. There may also be stuff on cleanflametrap.
 
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