| Author | Message | ||
| Mike Procopio (Pupz308)
Member Username: Pupz308 Post Number: 534 Registered: 10-2002 |
Well, it was complex. It was indeed the fuel pump. The pump wasn't getting pressure below a certain voltage (battery was low due to lots of electrical work I was doing in previous two weeks). I think I finally settled on that <10> 10 volts, it would pump strong. Should the damn thing still work with a low voltage, though? Wouldn't it be a linear degradation in PSI the lower the voltage, and not all of the sudden just not pump once a certain minimum voltage is not maintained? | ||
| Mike Procopio (Pupz308)
Member Username: Pupz308 Post Number: 522 Registered: 10-2002 |
Well, I removed the left rear wheel well and have done a fair amount of work down there at the pump. The pump *was* pumping a small amount of fuel (output line into glass jar), but was is small that it was not registering on my PSI guage (0 to 100psi). The pump was very quiet. Turns out, it was drawing 1.0A. So as I was measuring the current, I would apply current and then break the circuit a few times, it actually seemed like I *primed* the pump. Up it went up to 1,2, 5, 8, 10psi. *Sometimes*. When it did this--actually generate pressure--the pump would sound "normal," like I was used to. Sometimes when I connected the leads, it wouldn't pump, and it would sound quiet. When the pump was actually pumping fuel, I it would pull 1.25A of current, at 11.2V - 11.5V. I just replaced the fusebox, my mechanic seems to think flakiness in the electrical system could have caused the pump to fail. (Sigh.) Looks like the fuel pump is going back and I'm getting a new one. Will post back when it's installed. --Mike | ||
| Mike Procopio (Pupz308)
Member Username: Pupz308 Post Number: 517 Registered: 10-2002 |
Well, I just got the car to fire up... using starter fluid, that is. A quick, light spray of fluid down each of the carb barrels and I was running for a few seconds--and then nothing. This is the behavior consistent with the carbs not getting fuel. Since the fuel pump is being weird, my next move is going to be to swap it out. I had a bendix pump that failed, this is a Facet pump (which also has apparently failed). At this point, I'm thinking of going back to my old Corona pump (that started making noise and was "proactively" replaced!  ) Is it abnormal to have two bad pumps in a row? Is there something electrical that could have contributed to this failure (I just recently got rid of the old fusebox). My mechanic remarked that there was something "weird" with the fuel pump fuse and that he believes that caused the failure of the original replacement Bendix pump... | ||
| Mike Procopio (Pupz308)
Member Username: Pupz308 Post Number: 515 Registered: 10-2002 |
Do these cars have a "Fuel pressure regulator?" Could this be a blocked fuel filter? I'm on my way to check for fuel flow via the 7/8 carb line now. | ||
| Mike Florio (Mike_in_nevada)
New member Username: Mike_in_nevada Post Number: 43 Registered: 6-2003 |
Checking the return line doesn't check if there is fuel in the float bowls. While it is unlikely that all four float needle valves are stuck, its a possibility. I've seen cases where people used those needle valves with the rubber point end, and they reacted with something in the fuel and melted themselves shut. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 2105 Registered: 1-2001 |
Mike -- Alternatively, you can check for fuel flow presence by pulling the return line going from the 7/8 carb to the RH side fuel tank and use a collection jar per Peter B.'s suggestion -- not that you won't probably be pulling the left wheel well eventually (don't like that "audio" behavior you report), but less disassembly required for the test (please be careful). | ||
| Dr. I. M. Ibrahim (Coachi)
Member Username: Coachi Post Number: 373 Registered: 5-2002 |
I have had similar problems with my 308. If you don't hear the pump humming, then you have a poor connection at the fuse box. I would suggest that you jiggle your fuel pump fuse and you might have a solution to your problem | ||
| Hamlet Zadourian (Mysteven)
New member Username: Mysteven Post Number: 10 Registered: 2-2002 |
Just don't pump to much since it is quite easy to flood these engines with 8 Webers on top of your motor. This could easily cause a secondary problem, if not, it may be the problem. Good Luck. | ||
| Mike Florio (Mike_in_nevada)
New member Username: Mike_in_nevada Post Number: 42 Registered: 6-2003 |
The float bowls are not visible through the carb venturis. You have to remove the top of the carb, and the float and valve comes with it. One way to check for fuel in the carb bowls is to have someone pump the accelerator pedal once or twice with the key on and the pump pumping. Look for a squirt of fuel into the venturi. If you use a light use a flourescent or better still, a small flashlight. i don't like the idea of a hot incadescent light around squirting fuel. | ||
| Mike Procopio (Pupz308)
Member Username: Pupz308 Post Number: 514 Registered: 10-2002 |
Good tips--the first thing I'll do is check for flow on the output of the fuel pump. On a related note though--when I look down into the throats of the carbs with the top of the airbox removed--am I seeing the float bowls? Should I see fuel in here? | ||
| Peter Barbin (Sophia)
New member Username: Sophia Post Number: 28 Registered: 8-2003 |
Mike, I'd check for spark next...Have spark? Smell Fuel? Spark Plugs fouled? Then go forward toward fuel delivery. If fuel is the path you're going to check, I'd go the route of pulling the left rear wheel and the wheel fairing...You'll be staring at the fuel pump in the front of the wheel well. Check for power at the fuel pump next with the key in the 'energized position.' Power good? Then pull the fuel line off the output side going up to the carbs...afix a short piece of fuel line to the assembly...get a collection jar...key on. Got fuel flow? That was very basic, but I hope this gets you going down the correct path. Of course there are countless other ways to accomplish these steps, I go for the back saving variety approaches.Good Luck! | ||
| Mike Procopio (Pupz308)
Member Username: Pupz308 Post Number: 513 Registered: 10-2002 |
My 308 has been down for two weeks while I've had the rear calipers rebuilt. I just got the calipers back on, and the car won't start. The battery is strong (currently 11.5V after two weeks), optima red top. All accessories work. The starter sounds good, I get a really strong crank when I turn the key. I suspect the fuel pump. Although new (Facet), it is behaving very strangely. Normally, when I turn the key to charge the fuel system, I hear the pump running pretty loudly as the pumps fuel. Then, around 10 seconds or so, when the float bowls have been filled, the fuel gets recirculated and this causes a different, quiter sound. My problem, I think, is that now, I get .15 seconds worth or the loud sound (just an instant, really), and then it goes quiet again. The fuel pump is drawing some 11 volts, and is pulling 0.2 amps; that sounds about right to me. When I press on the fuel lines around the pump, I can press them in all the way--they don't feel pressurized (SHOULD they be pressurized)? How can I tell if the carbs are getting fuel w/o taking off the air box? If I take off the top of the airbox, and I look down the throats--I can see metal. Am I looking at the bowls here? Should I be able to see fuel? I do not see fuel there... The fuel pressure regulator has not been changed on this car, ever to my knowledge... Is there a way I can check fuel pressure? Any ideas? I'm thinking I need to check the carbs for fuel and check the fuel pressure after the filter. Am I on the right track? I just got the rebuilt calipers back on and want to get this car out where she belongs! Thank you... --Mike |