I don't hear my fuel pump(s) running when before the engine starts and the key is in the on position. Shouldn't they run, build up pressure, then shut off till the engine starts?

After I start the engine I can reach under the car and feel the fuel line surging with the pump.

I've wondered if this is why mine starts sluggishly. It cranks for a moment then casually builds up rpm over a couple of seconds till it's idling regularly.

My Volvo 850, Nissan, Ford, Dodge and any other FI car I've had runs the pump first, cranks a few turns then instantly starts and runs at idle.

Thanks,
--
Erwin in Memphis, '88 745t 193,000 miles, '95 855t 96,000 miles

Hi! I own a 1990 740GL which uses the Bosch system. If I set my key to "On" but do not continue on to start the car, my fuel pump (this car has only one, an in-tank high pressure pump) does kick in for a few seconds and can be heard even with the door closed.

Hope this helps you somewhat.

Older LH cars run the FP when the key is turned. If the engine doesn't start you should hear the fuel pump running for a second.

Newer LH cars run the FP when the key is turned to "on" whatever "KP" that is. But it only runs for a second or two.

None of my 86-88 cars run the main pump until the engine turns over.
We've got 4 examples here that I'm intimately familiar with. They do start running the main pump the second the engine moves.

Also, unrelated but both the 88 740's are hating this cold weather... both have had a slow-cranking, foul-the-plugs, no-start morning, just one time.
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 225K, 88 744GLE- 209K, 91 244 183K. Also responsible for the care and feeding of: 88 745GLE, 229K, 88 244GL, 146K, 87 244DL, 235K, 88 245DL, 236K

"None of my 86-88 cars run the main pump until the engine turns over."

That was my point...

Old: Turn the key to 'start', FP runs. Let off before it starts, hear it run for a second.

Newer LH models, the FP does a prime cycle when the IGN is keyed to 'on'.

ANyway....

Hey, at least it does start! Runs pretty darn well too! My two Volvo start like my two kids. One jumps out of bed with a full head of steam, (boy, 850) the other takes longer for the boiler to come online, (girl, 740).
--
Erwin in Memphis, '88 745t 193,000 miles, '95 855t 96,000 miles

I should have known to look in the FAQ first. I just found that the pumps don't run untill the engine starts.

From the FAQ:

"1. Fuel Injection Relay Test. There are 2 relays inside the fuel injection/pump relay. One of them should turn ON when the ignition is turned on (without turning over the engine), and the other relay (which actually turns the fuel pumps) should come ON when the engine turns over/runs. You can check the 1st relay by putting your fingers on the relay module and turning the ignition on and off repeatedly. You should feel the relay click on every time. If it doesn't, that relay isn't working. And you'll find the car doesn't start if the relay did not come on."

AND:

"2. Fuel Pump Diagnostic Tests. On the 740, the fuse-box + relay box can be pulled out a little to facilitate inserting/removing relay modules. So pull it out as much as the wires will allow. Pull out the fuel injection/pump relay module. Now take a small piece of wire to jumper terminals 30 and 87/2 on the relay board (the terminals are identified on the relay module pins. The 2 terminals are the nearest left and middle right pins on the relay board). This should make the car act like the fuel pump relay is ON.

Now turn the ignition ON (without turning the engine). You should hear a whirring sound right from where you are. That will be the main fuel pump. Now go to the gas tank and unscrew the cap. Put you ear to the hole and you should hear a smaller whirring sound. That will be the in-tank pump. If you hear both noises, the fuel pumps should be OK."

Until I actually check fuel pressures at the rail while running, after shutoff and before the first start in the morning I'll live with the tractor-like starts.

--
Erwin in Memphis, '88 745t 193,000 miles, '95 855t 96,000 miles

If your system is like the LH 2.4 in my 93 245, you will hear the pump run, IF the car has not been running for 3 minutes or longer. Inside of 3 minutes from shutting off the engine and the pump won't run. I assume it's because the LH ECU thinks the pressure hasn't bled off anough to require a repriming of the fuel rail.

Hi Erwin,

Yes , you're right, you should be able to hear the fuel pump for a couple seconds when the key is in the ON position. I usually let the pump 'prime' (stop at ON for a few sec) before I start my 740s in the morning. My turbo does something similar to what you discribe as in it starts and then the RPMs build. It's a bad check valve in the fuel line in my case meaning that the fuel pressure is allowed to bleed off when the car is turned off. I just haven't bothered to replace it because it's not worth the $40 to me. The car starts strongly, it's just that it doesn't get it's gas right away because of the bad check valve. This is very likely the problem with your car as it's a common failure. I hope this helps.
--
Chris. Halifax N.S. '91 745Ti, 287K km and '91 745 NA, 362K km.

Thanks,

Where's the check valve? In the pump? "When I get time" I'll build up a fuel pressure gauge adapter and let it sit overnight, but for the time being, if the valve is readily replaceable I might try a salvage yard replacement.

--
Erwin in Memphis, '88 745t 193,000 miles, '95 855t 96,000 miles

Chris,

I think your pumps run with Key ON because they are '91s, and probably have the LH 2.4 FI. Erwin's '88 is probably LH 2.2.

I have no real proof on this, but in my own experience, no LH 2.2 does it*—while the '93 940 does. And I've seen it on one '89 240 (LH 2.4)

* The exceptions are when the engine stops with the Hall Sensor in just the right place to furnish a brief pulse with power ON. This allows the pumps to run for a second. But it's not a design feature, as I believe the LH 2.4 to have.

P.S. I also think the Check Valve's been getting a bad rap. The spec is that it mustn't drop below 14.5psi (more then half) in 20 minutes. What can you expect in the morning?

I believe it's more to help on repeat starts during routine usage. This is borne out by the fact that it's purpose (in maintaing some pressure) is described as being for "quicker restarts and preventing vapor lock" (Bosch FI manual).


Just my observations,

Bruce

--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Sold 5/03)
'83 Turbo 245
'76 244 (lasted only 255,000 miles)
73 142 (98K)
'71 144 (track modified--crusher bound)
New 144 from '67 to '78
Used '62 122 from '63 to '67

Hi Bruce,

Good point about the different fuel systems, I didn't think of that. My turbo has LH 2.4 I believe and the non-turbo has Regina. In both of mine the pump cycles with the key in the ON position. The Regina sometimes stalls right after cold start, but then starts and runs fine, I figure it's the idle control motor having a hic-up, lol. As for the check valve, I say it's common from personal experience and what my mechanic says....but your spec does make sence.


--
Chris. Halifax N.S. '91 745Ti, 287K km and '91 745 NA, 362K km.

Hi Chris, Thanks for your response. I forgot one other thing that supports the 2.2 – 2.4 theory...

The 700 (88–) Fault tracing manual (Regina) has this for the first step in No-Start diagnosis:

"The fuel pump should pump for approx. three seconds after the ignition has been switched on."

I don't have the comparable LH manual, but the '93 Greenbook shows both FI systems, and except for external differences (like AMM vs Air Temp Sensor), the LH 2.4 and Regina systems appear almost identical.

Admittedly, it's a stretch to assume that the LH 2.4 has the same diagnostic as the Regina, but the circuit similarities suggest that it's likely.

And since I have never seen the "Key ON = Pumps Run" suggested in any published LH 2.2 maintenance literature, I see it as an occasional fluke that's become a myth.

P.S. My Regina starts after the 2nd compression stroke (or so it sounds) in sub-zero temps. I've heard there was a "Cold Starting" ECU upgrade some years ago, but you probably have that already, in Halifax (where the Volvo assemblers use red Loc-Tite on the brake hose fittings — the 900 at least).
--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Sold 5/03)
'83 Turbo 245
'76 244 (lasted only 255,000 miles)
73 142 (98K)
'71 144 (track modified--crusher bound)
New 144 from '67 to '78
Used '62 122 from '63 to '67

Well, thanks for the info Bruce! I get most of my info from my Volvo mechanic, experience, this form, and occasionally a Haynes manual :) I worked for my Volvo mechanic last summer, that was fun! :) I learned TONES about Volvos. I quickly became the second Volvo "expert" that customers asked for, lol. I felt bad for the other mechanic, but he was more interested in VWs. Anyway, I don't know if my NA had the ECU upgrade....probably...I just bought it this summer with about 352K km on the clock. I've had the turbo (my first Vo) since Oct '01 and ~241K km. I've gone through a lot with both of them, namely an engine rebuild on the turbo (done by my mechanic). The turbo is my baby which I decided not to drive this winter, although I'm growing fond of the NA despite it's issues here and there...Wish I had a better place to store the turbo for the winter, but dad's '93 Vigor (which I also like a LOT) is taking up the only garage space, so the turbo is outside in a tarp 'hut' on jackstands with a rubber lined floor under it and a light car cover on it. I think it'll be ok, just not as dry as would be preferred. Have to build a garage before next winter! Anyway, enough babling from me, lol. Oh, I didn't know that about the Loc-Tite...haha...A REAL good old body work man that we use once in a while use to work at the Volvo plant here, his stories are GREAT!....And so is his metal work! Wow. One more thing....Yeah, the Regina starts different then the LH 2.4. The turbo starts in a flash and the Regina seems to work harder....could be the Shell Rotella-T 15W40 too, LOL....Na, I think it's the Regina....The turbo uses Amsoil 10W40 :)
--
Chris. Halifax N.S. '91 745Ti, 287K km and '91 745 NA, 362K km.