Car stopped suddenly. With air flow sensor pulled up/on fuel pump only comes on for about 1-2 second at the end of a starter cranking cycle as you release the key (very consistent ). I swapped out the 2 relays on the front drivers side fender near battery with relays from junk yard. No change. One relay is small cube (5 terminal) with terminal #'s similar to one in manuel. Other is larger rectanglular (6 terminal). Are these fuel pump and main relays. Any other relay on fuel pump circuit? Small cube relay terminal 87b goes to Control Press Regulator but not to Aux. Air Valve. Both sides Aux. Air Valve are grounded. 12VDC jumped to wire from term.87 should turn on pump no go. Is it also controled else where. Pump seems good. Is this a relay problem? With both relays bad? I found no switch on the air flow sensor don't believe it exists on this model.
Thanks Marcus
244 1979 B21F engine Fuel Pump Won't Run for Long
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billofdurham
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Welcome to Matthew's Volvo Site.
In the Haynes UK book the two relays you mention are the main or safety relay, to the rear with 5 terminals, and the fuel pump relay, to the front with 6 terminals.
Although this is the UK book it does have wiring diagrams for US models. I can't find any other relay for the fuel system but there are 3 fuses: #5 - 8amp, fuel pump (feed); #7 - 16amp, main pump and #13 which is the pump relay but also covers instruments, turn signals and seat belt warning.
On the wiring diagram the main relay has terminals 30; 85; 86; 87 & 87a but does not show 87b. The fuel pump relay has terminals 15; 30; 31; 31b; 87 & 87b.
On the main relay 30 draws supply from the fuel pump relay; 85 goes to the air-fuel control unit; 86 which is linked to 87a goes to the ignition coil (terminal 15) and 87 goes to the starter motor.
On the fuel pump relay 15 goes to fuse 13; 30 goes to fuse 7; 31 goes to earth (ground); 31b goes to the ignition coil (terminal 1); 87 to the fuel pump and fuse 5 and 87b to the control pressure regulator and the auxiliary air valve.
Difficult/no start on a cold engine can be caused by:
Fuel distributor or airflow sensor sticking.
Line pressure low.
Control pressure too high.
Auxiliary air valve not opening.
Bill.
In the Haynes UK book the two relays you mention are the main or safety relay, to the rear with 5 terminals, and the fuel pump relay, to the front with 6 terminals.
Although this is the UK book it does have wiring diagrams for US models. I can't find any other relay for the fuel system but there are 3 fuses: #5 - 8amp, fuel pump (feed); #7 - 16amp, main pump and #13 which is the pump relay but also covers instruments, turn signals and seat belt warning.
On the wiring diagram the main relay has terminals 30; 85; 86; 87 & 87a but does not show 87b. The fuel pump relay has terminals 15; 30; 31; 31b; 87 & 87b.
On the main relay 30 draws supply from the fuel pump relay; 85 goes to the air-fuel control unit; 86 which is linked to 87a goes to the ignition coil (terminal 15) and 87 goes to the starter motor.
On the fuel pump relay 15 goes to fuse 13; 30 goes to fuse 7; 31 goes to earth (ground); 31b goes to the ignition coil (terminal 1); 87 to the fuel pump and fuse 5 and 87b to the control pressure regulator and the auxiliary air valve.
Difficult/no start on a cold engine can be caused by:
Fuel distributor or airflow sensor sticking.
Line pressure low.
Control pressure too high.
Auxiliary air valve not opening.
Bill.
Work was good - retirement is better.
1996 850GLT 2.5 20v Estate Manual.
1995 Peugeot Boxer 2.5Tdi Autosleeper.
Previously:
1984 244DL, Manual, Beige.
1987 744GLE, Manual, Green.
1991 960 3.0 24v, Auto, Silver.
1994 940T Wentworth, Auto, Blue.
1996 850GLT 2.5 20v Estate Manual.
1995 Peugeot Boxer 2.5Tdi Autosleeper.
Previously:
1984 244DL, Manual, Beige.
1987 744GLE, Manual, Green.
1991 960 3.0 24v, Auto, Silver.
1994 940T Wentworth, Auto, Blue.
I found some time to work on this. Found the fuel pump relay under the dash left of drivers left leg. It is an electronic relay -- 2 transistors, 6 leg IC chip (OP Amp?), caps, resistors and diodes. It does turn on at end of crank cycle.
I decided to crowbar a solution and jumped power from fuse 4 to 5 which should power up both fuel pumps. I can hear a pump running but get no fuel out injector. I remove injector nozzle and I get fuel flow out of the line. Must not be building pressure. I've not measured the amount but appears enough to run a cylinder. (I have air flow sensor plate jacked open.)
I can't find a leak. A bad pump seems odd, sounds like its running and this car stopped running suddenly. It does deliver some volume although that might be done by the tank pump. Could a problem with Line Pressure Reg. cause this? Relief valve at pump stuck open?
I decided to crowbar a solution and jumped power from fuse 4 to 5 which should power up both fuel pumps. I can hear a pump running but get no fuel out injector. I remove injector nozzle and I get fuel flow out of the line. Must not be building pressure. I've not measured the amount but appears enough to run a cylinder. (I have air flow sensor plate jacked open.)
I can't find a leak. A bad pump seems odd, sounds like its running and this car stopped running suddenly. It does deliver some volume although that might be done by the tank pump. Could a problem with Line Pressure Reg. cause this? Relief valve at pump stuck open?
I have a '78 242 with the B21F also, I was messing around with the interior the other day, and had the car running to keep me warm... anyways, I bumped into the relay by the drivers leg for the fuel pump... Mine was hot, I am just wondering if your's possibly has been getting hot too, and maybe decided to fail? Or is your relay's all good? I know it is the fuel pump relay cause as soon as I unplug it, the car idles to a stumbling stall.
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