Just wondering can anyone out there gimme the preasure specs for a Mechanical Fuel Pump on a 71 L6 200 CID? Seems my Fuel System prob has returned (Carburetor not getting Gas) Last time this happened I checked the pump it was fine (had suction at least) I poured Gas in it and the car ran for awhile I think I only did a Band Aid on the problem though. Probably gonna end up dropping the Gas Tank and checking the fuel sending unit, but before I do that I figured i'd run a Vacumn Preasure test on the pump to make sure it's operating the way it should be just need to know what reading is considered normal for that type of pump. 71 Grabber (Project Car) 85 Club Wagon 94 Taurus GL Sedan FFV
Fuel pressure should be 4-6 lbs. I take it that You installed a new fuel filter already,You don't have to drop the tank to check the pick up tube,only takes a few mins to to remove and reinstall. Also You may want to try blowing air back to the tank from the suction side of the pump,this may unplug the pickup screen for a little while anyway!
Sounds similar to what happened to me a few years back. The bolt holding the fuel pump eccentric on the end of the cam backed out, and I started having problems with the car dying with no fuel getting to the carb. I replaced the fuel pump to no avail, then found out about the eccentric that drives it (fuel was getting to the pump). I pulled the timing cover off to discover the problem, bolt had backed out and started wearing the inside of the timing cover, and the tab had broken off the eccentric that keeps it from spinning. Had a time locating one, but got it all back together and everything was fine.
Yep new filter installed a couple months back checked it recently while I had the line off still in good shape. I hooked up a portable air compressor and blew air through the line with the Gas cap off heard entering the tank but no bubbling noise almost as if pick up screen was sitting above the fuel level (my gauge shows 1/2 tank almost). Gas tank does have a rather sizeable dent near where the sending unit goes in almost as if previous owner backed into a boulder or something not enough to puncture the tank but certainly enough to damage it. Thought about removing the fuel filler neck only without dropping the tank to see if I can get a better look at the sending unit now that I got my trunk open (Latch was busted key did not work so I removed the whole latch unit from inside the trunk with back seat removed. I'm not a small person so this was no easy task ) Knowing my luck though i'll get the filler neck off but won't be able to put it back on, gotta pound out that dent though somehow I don't feel like buying a new tank unless I absolutley have no other choice cause I know they can be expensive. Anyhow thanx for the input pplz i'll post a progress update soon hope it's a good one . 71 Grabber (Project Car) 85 Club Wagon 94 Taurus GL Sedan FFV
Joe, like Tom said, you will never have to remove the tank unless you are replacing the tank. The sending unit and strainer come out the bottom of the tank. But before you do anything please just buy a fuel pressure/vacuum gauge (if you don't have one, they are around $10) and check your pressure!
There is one exception to never having to remove the tank, and that is under extreme conditions, such as dirt in the tank, or in one case that I came across, the screen came off of the pick up, and was being sucked up by the pickup, causing no fuel flow. I had to pull the tank tosee what was going on inside. Has been a while, but My mav has the same prob, new fuel pump, no fuel flow. Can the pickup be unscrewed with the tank in the car, and is there enough room to stick my arm in the tank to feel around with out removing iT?
Well the fuel pump checks out (I think) my gauge only measures in Hg and KPA. I have a Vacumn Hand Pump that I bought awhile back says on the package it can test Mechanical Fuel Pumps hope so cause i'm beginning to run low on cash. Anyhow I hooked it up cranked the engine vacumn gradualey increased eventually steading around 15 hg probably would have gone a bit higher but I didn't wanna burn my starter out. Ran a second test for good measure same result. As for the sending unit I read somewhere that it is held in by a locking ring that you tap off with a screwdriver then just pry the sending unit out. Hopefully mine is intact and just obscured by the dent I mentioned before I went to three different auto parts stores (AutoZone, Napa, and Kragen) none of them carry fuel sending units infact the guy at Kragen didn't even know what I was talking about (kept thinkin I was refering to a tank mounted fuel pump), all told me i'd have to go to a Ford Recycling Yard or somethin. Seems like i'd have far less hassle just buying a new tank . 71 Grabber (Project Car) 85 Club Wagon 94 Taurus GL Sedan FFV
15" of vacuum is more then adequate to pull fuel from the tank,now Your pressure should be 27.58 to 41.37 KPA,that's 4 to 6 PSIG!
Pulled the filler neck off today surprisingly is came right out with minimal force required once I unbolted the part where the Gas Cap screws on, did this only to discover that I still couldn't see inside the tank cause of a tunnel that runs about a foot forward from where the filler neck slides in. I thought maybe If I could see where the fuel level was and where the sending unit was I could figure everything out.. *sigh* oh well learn somethin new everyday. Mavs (and infact Automechanics in general) are still a new field for me learnin as I go here. Guess the only thing left to do now is drain the tank and try to get that sending unit off. I did order an AutoKrafters catalog yesterday can't wait for it to arrive there is a ton of things I need for that car. Thanx for all the input pplz. 71 Grabber (Project Car) 85 Club Wagon 94 Taurus GL Sedan FFV
Another thing you might check is the 2 rubber hose connections under the car. There is one at the tank and another just behind the tork box (located about where your left foot rests). If the original clamps are still there they can allow air to be sucked in. This happened to me on a 79 Bronco I had. It would just die about every 30 minuits, then start right back up after a minuit of cranking. Took me a good while to find that one. I replaced the pump twice, dropped the tank twice, and rigged an electric pump for testing, only to find out the clamps were too weak. I found it by plugging up the hose at the tank and pressurizing it from the front. I put new screw clamps on and never had another problem
I almost forgot about that thanx for the tip, I replaced the one that connects to the tank the last time I had this problem didn't help but the hose needed replacing anyways due to cracking. Didn't mess with the other one though I still have a bit of fuel hose left over cause Napa sells em by the foot so i'll replace the other one too it is worth a try . Those spring clamps do suck, my biggest beef about em is if I accidentally get em caught on my finger thats happened a few times don't feel too great also they seem to loose their grip after a few use's don't last too long. I might also replace the hose that connects the main line to the pump even if I fix the problem may as well prevent another one down the road. 71 Grabber (Project Car) 85 Club Wagon 94 Taurus GL Sedan FFV
How do I keep the Gas from spilling everywhere then? You'll have to bare with me i've never messed with Fuel Tanks before this will be the first time i've ever attempted this.. Tried a little experiment earlier today one last ditch effort to see if I can fix the problem without removing the sending unit I removed the connecting rubber fuel hose and shoved a siphon hose up inside the outlet tube I noticed black like sludge and alot of brown residue (rust and varnish I presume) on the siphon hose as I pulled it back out. I thought maybe I could unclog it if it was clogged cause blowing air in there wasn't doing any good. Failed to siphon any fuel out either. 71 Grabber (Project Car) 85 Club Wagon 94 Taurus GL Sedan FFV
You jack up the rear drivers side,the fuel is now on the passenger side away from the sending unit,a few taps with a drift punch or screw driver on the retaining ring and "wha La" You have the sending unit out.
