fuel pressure woes
 

1995 940 turbo wagon (2.3) has no start and was showing 13psi key on. After checking all other possibilities (I thought) I have replaced in-tank fuel pump as this system has only one pump. Although filter seemed ok, replaced it too. I now have no fuel pressure at all! A check of voltage coming to the last plug-in connector before the pump shows no voltage between the big red and big black wires (key on). Fuses good, relay clicks, so I pulled the relay and opened it up. Using battery voltage between posts for the coil on each relay does make them move, and all contacts look good. Even used short spray of electric contact cleaner and dried them. Am I missing something? Guess I'll rig a tester across the working points of these relays and operate the coils to see if juice flows, but I expect them to work. Can't seem to find a good description of how this circuit is suppose to work. I believe with key on pump should run 2 sec and bring up normal pressure 35psi. Understand that then when cranking mass airflow sensor somehow tells pump to run. Is this correct? What else can interupt this circuit? Car was running a few days ago and then next failed to start but would crank and cough and almost start if gas pedal was slighty depressed. Right now the only thing depressed is yours truly. Any ideas are grately appreciated.:confused:

Do you have power at the pump (good relay and power wiring), but no power across positive and negative at the pump (bad ground/pump assembly)? You can power straight to the pump from the battery to make sure the pump is good. Turn on key and listen for pump. If no pump, then jumper the relay socket with a switch, turn key to ON position and use switch to turn on/off power to the pump. If pump runs then bad relay.

more info
 

Thanks for the help. Turns out when I soldered new connector ends to fuel pump wiring, got a little solder inside of connector, just enough so that it would not fit the pump spade connector. When I pushed the new plastic locking terminal onto pump, that fouled connector pushed up out of the plastic holder and was not connected! How did I miss this you ask? Darned if I know. Just tired I guess. Bad news is although car now runs, I'm back to the same original problem = turn off car and after short time try to start again and sputter, cough hold pedal 1/2 way down and it may start and run rough for a bit and finally clear. I'm now thinking leaky injectors flooding engine. Any easy tests or cures? Thanks again for all those responses.

What is your fuel pressure now, while it runs, and what is the residual pressure after shut off and how long does it hold? If you turn the key 2-3 times (running the pump) before trying to start, does it start easier(bad residual pressure) or worse(possible flooding/leaky injector)?

Start with the easiest and rule out the regulator first.

new woes
 

Was going to test fuel pressure running and for leak-down, but with car sitting for 8 hours, will not start and acts just like same old problem that always happened as hot start issue before. Tries to start but coughs and stumbles and pressing gas pedal helps but not enough to actually start. Does this B230FT engine have a cold start valve? If so, where? Thanks.

Since you had a fuel pressure problem before, I suggest making sure that's fixed first. If you are cranking and still getting low fuel pressure, I would start there. Did you use a factory pump, or just replace the internal pump with a Walbro? I did that with mine a few months ago (cheapest I found the factory pump was $500, so I tried to beat the problem with a cheap one), and I still only had 12psi running and 0psi residual. I verified everything again, and bit the bullet on the factory pump. Started right up (extended crank before) and had 41psi.

Not saying it's your issue, but don't take for granted that the new pump is working correctly.

I don't see a cold start valve on parts for sale.

more info- no fix
 

Fuel pressure now 43 psi after turning key on and off 3 times. Residual pressure had to determine since I can't get the test rig to stop leaking some. Replaced all o-rings and still leaks! Any how, I think fuel pressure and delivery is ok. Since then have removed and cleaned EGR valve (didn't seem very dirty). Ran across advice that said disconnect TPS and see if car starts, and it did, though not perfectly and had to rev some to clear excess fuel? and some dark smoke. Hooked TPS back up and car still starts and runs but test run had one moment when slowing to stop car started to die, but pumping gas kept it running and ran normally the rest or that run. New TPS is $36 my cost. Should I replace or is there a good test?

Now wonder about possible ECU problem so tried to get junk yard unit, but closest match was from a 1991 940 turbo B230FT car and that ECU has slightly different number (Bosch 0 280 000 939). Would the 91 computer be different for the same engine due to different sensors feeding it, or should this work. I've been afraid to try it. Already put the 95 computer back in and failed to write the number down (rats) but I think all numbers were the same except the last three. Can get that number if it would help. Thanks again for any ideas you may have. I am about out of ideas and hate pouring parts and $ into this car which I plan to sell. Just can't bring myself to sell it without a solid cure,

You are now into a very open realm that could be anything. Clean the grounds. Is the check engine light on? Can you narrow it down to if it is more related to cold or warm startup/running conditions? You need test procedures for the AMM, coolant temp sensor and ECU. Maybe someone can provide. Clogged injectors are possible (anything restricting fuel flow). Idle valve could be bad, if the stalling is only when coming to a stop.

Still no-fix
 

Thanks for your input, but note: No check light, no codes set, all grounds checked and tightened, failure seemed to occur mostly after running, then sitting 20 minutes or so, but 2 days ago happened after sitting for 8 hours in nice dry sunlight! IAC has been cleaned, and then swapped for junkyard unit. What is the AMM? Is this air mass meter? Have not checked the coolant temp sender as problem is so intermittent didn't think this would be it, but I will try a swap. Can't seem to find ECU information on the net, but am thinking this could be the issue. My 1995 ECU shows bosch # 0 280 000 954, car manufactured 03/95, vin YV1JW8618S1154755. Closest junk yard match was 91 940 turbo, ECU# 0 280 000 939. Can anybody tell me how different these are and will this work to test for my issue? My local boneyard say my ecu should swap with certain year nissan/datsun 240's. Anyone got a Hollanders to check this out? Thanks again for your help. These intermittent problems are always the hardest.

Yes, air mass meter. I don't know these cars, so the devil is in the details. Some cars will have a heat soaked no start condition with a failing AMM, while others go into a limp mode, but will still run. the ecu can heat up and be intermittent also.

has it ever stalled while driving? maybe a hall effect sensor problem, like the crank sensor?

more info
 

Thanks again. Crank sensor was the very first thing I changed as I have seen these be very intermittent. No joy. I tested ignition module 3 times while tapping on it and checks ok. Another gearhead also says AMM possible and says when failure occurs, disconnect it and if things improve, change it. After r+r ignition module, cleaning other connections and grounds, car has not failed again, but only a few hours and trys. I'll let you know as if your like me, you would like to know what works. VTY the rusty one

Yes, some cars you can disconnect the AMM, which puts the car in limp mode. If the Volvo is like that (SAAB is), then the AMM should not keep it from starting. Someone just needs to let you know the particulars, so you can test it.