Hey guys, need some quick validation here...I think my fuel pump is shot but just want to confirm that my observations are pointing me in the right direction.

I let the car sit for a few weeks in the fall and it wouldn't start when I tried to get it going to move it. I've been driving the car problem free for the last three seasons. So I built a car shelter over it and let it sit for the winter...but that's a whole other story.

Had some good weather and more light today so I figured it was time to see about bringing her back to life. '71 Cutlass with stock 350 and stock fuel pump.

- Car won't fire or cough just cranking, but turns over fine
- Car will fire for a couple seconds if I pour gas down the carb but won't idle or stay running
- No fuel in the line from pump to carb after a lot of cranking
- Pulled the fuel pump, no gas in the line to the tank either, but there is gas in the tank (about 1/4 tank). I'm assuming that's normal and the pump has to pull the gas forward. Should there be gas in that line regardless, indicating a blockage back towards the tank?
- Fuel pump makes sucking noises when I activate the lever but didn't seem to suck any gas in when the hose was put into a container of gas. Nothing came out the outlet pipe either.

Fuel pump shot?

 

It could be the check valves in the pump, but it also could simply be a bad rubber hose on the suction side. There are lengths of rubber hose between the tank sender and the frame hard line, and between the hard line and the pump. Since these are on the suction side, they may not show a leak when the car is parked, but any cracks in those hoses can definitely cause the pump to suck air.

 

To properly test your fuel pump run fuel IN to the pump from a jerry can with a lenth of rubber hose. Then run the fuel OUT of the fuel pump into an empty coffee can or pan. Cranking the engine should cause the fuel pump to activate and fill the coffee can.

You won't be able to activate the fuel pump properly if it's not installed on the engine. If the fuel pump doesn't fill the coffee can you know it's bad. If it does pump properly then you could have another problem like the check valve in the pump or dry rotted hoses like Joe mentioned.

 

You may not have enough fuel in your tank. Add 5 gallons and see if it flows from the tank to the fuel pump.

 

I'll be following the advice of Olds64 and oldcutlass tonight to see where that leaves me. Trying to eliminate one thing at a time.




I'm not sure if this may be related but last fall the gas gauge stopped working for a few days, just sat on Empty. It started working again before I had a chance to start looking into it.

 

Try pouring gas into the float bowl vent tube so there is enough gas for the engine to run longer. I use a small funnel for this and fill the float bowl so the engine runs long enough to pull fuel through the system.

 

I used a syringe and fed some gas down the vent tube; engine didn't catch at all. Added some gas down the primaries and the engine will fire briefly but won't idle. Briefly is about 1 or 2 seconds.

I haven't had a chance to look into any of the other suggestions yet but the result of it not running with some gas in the float bowl concerns me. Or maybe it needs more gas than 3 or 4 small syringes gave it?

 

Depends upon the size of the syringes. Many small ones are 10-20cc or so, which isn't enough to fill the float bowl. I typically pour an ounce or more into the float bowl, then a dribble down the carb bore to get it started.

That indicates how much fuel you injected. It's getting burned very quickly so you need to add more than that to the float bowl.

 

Get your self a vacuum/fuel pressure gage and see if your pump is putting out at least 6 psi of pressure. If not, it is bad. If it is putting out pressure, you have another problem.

 

I had to dribble some into the bore before it would do anything and then it was the same short spurt as before I put anything into the bowl. I'll try again with more tomorrow...today I didn't want to overfill the bowl.

Fuel pump is still out of the car so no pressure testing of it yet. It might still be part of the larger problem but right now I figure I'll eliminate what I can without adding or removing any more parts. If there's enough gas in the float bowl then the engine "should" start and run/idle for more than what I'm getting now without the rest of the fuel system in place.

 

If you do this I believe you can rent a vacuum/pressure gauge from the auto parts store.

 

Why rent, they are cheap enough to buy easily.

 

Another possibility is that if you have hose splices in your line they may be old and not compatible with fuels containing alcohol, which is probably all nowadays. They can swell and choke off the line if enough rubber is exposed. Simply replace the splices.

 

Yes, you will have to either dribble fuel into the carb bore or actuate the throttle so the accelerator pump sprays fuel into the bore so that the engine will fire. After that, the air flow through the carb should pull fuel from the float bowl through the jets and out the venturi passages.

Don't worry about overfilling the float bowl as the excess fuel will help prime the engine by running down the bore.

Here's something to try: fill the float bowl then see if the accelerator pump squirts fuel. If it doesn't, try adding more fuel to the bowl to see if that results in an accelerator pump shot. If you don't get anything from the accelerator pump, you may have an internal issue with the carb.

Oh yeah, make sure you are pouring fuel into the float bowl vent and not into the air cleaner stud hole. The float bowl vent is the front one.

 

I'll give that a go tonight...I've been wondering about an internal issue at this point. The syringe was probably from my kid's cold medicine...measurement was tablespoons, lol. So I probably put 4 or 5 tablespoons in yesterday. Probably not enough yet.


I've been using the front vent with the angled opening.

 

Well, one of those "good news, bad news, worst news" scenarios.

The good: I put a lot more gas into the bowl today and a generous amount down the bores. She fired right up and settled into an easy idle.

The bad: I wish I had done that earlier! I still don't know if there are secondary issues in the fuel line (which was dry), fuel pump or sending unit (gauge acting up last fall). I'll get those questions sorted out soon.

The worst: I had a pretty good idea the timing chain needed replacing. In fact, I picked up all the parts last year and didn't have time to do it. Figured this was the ideal time to check it with the fuel pump out, and it is loose. I don't mean kinda loose, i mean "how come it still runs" loose. So that's my next big item as soon as I make room in the shop for it.

In unrelated news, my driver's door is stuck closed. Latch problem that's been developing. So another thing to take care of. And tonight is great weather for a cruise. Motivation!

 

Can you kindly elaborate this a bit because I am having the same issue here.
I have attached an image for clarity.






"run fuel IN to the pump from a jerry can with a lenth of rubber hose"

Does that mean I have to fill the fuel pump with fuel from opening #3?

"run the fuel OUT of the fuel pump into an empty coffee can"

Does that mean
1. I have to fill the pump from opening #3 until fuel runs out of hose #2 OR
2. I have to fill the pump from opening #3 and crank engine until fuel runs out of hose #2?

At what stage the metal line from carby should be connected to the pump #3 orifice?

 

Feed fuel to the pump from #1 like the picture. Now feed the fuel from the pump to the carburetor from #3.

 

When i took the picture, that can had fuel in it. Shouldn't fuel come out from #3 when cranking? Didn't happen so in mine. Never seen a mechanical pump pumping fuel out, so I've no idea how strongly it flows out. I did not run the starter over 5 seconds though.. isn't that enough to pump fuel out?

 

Put a hose barb and rubber hose on #3. Run the hose into a coffee can. Crank the engine for a good 10 or 15 seconds and you should see fuel gushing out the end of the hose into the coffee can. If there isn't positive flow you know the mechanical pump is bad.

 

Suddenly had a brainwave and coupled a spare electric fuel pump to fill the pump and carby.


then disconnected it and immersed the input line to a can of fuel.

engine only ran when spraying fuel to primaries. died when not.

sounds good though ☺

 

Oh yeah!

If it runs only while spraying fuel in the carburetor then chances are your fuel pump is bad. If you decide to install an electric fuel pump make sure you mount it on the frame as close to the gas tank as possible. Electric fuel pumps are designed to push the fuel to the engine, not pull it. There isn't any reason to run 2 fuel pumps. Good luck, let us know what you figure out.

 

Dear friends,

While the accelerator pump sprayed fuel in to both primaries, it leaked fuel to the top of the air horn too!

And the last time it ran, it coughed and stalled and flooded fuel out. There is the possibility that idle circuit is blocked. (I was spraying fuel to the primaries all the time it ran)

Then I removed the carb once again and took the air horn off.

Kept the screws in exact location


Half of the gasket was attached to the top part


The other half was attached to the bottom part, looks dissolved



Tip of the TPS was lying on the body


Tip of the TPS was broken


Cleaned surface. Needs repair kit


Dead end once again until the new parts arrive.

MCS could not be removed due to the head of the screw (think mixture enrichment screw - between acc pump and green MCS connector) was ruined (its not | shaped but < shaped). Have to make a careful cut so that I can use a flat screw driver to remove it. Then take out the float to clean the float bowl as it had mud like deposits

 

I just had this problem with my '69 4-4-2. Went through all the tests and, the bottom line was, the 2-year old fuel pump (that still looks brand new) was shot. A new fuel pump and about 5 seconds of cranking and the car started right up.

The carb was bone dry. I disconnected the fuel line between the carb and fuel pump - bone dry. I removed the fuel feed and return lines - nothing there. I siphoned fuel from the tank through the feed line - fuel there! Got the new fuel pump yesterday and put it in this morning.

Randy C.

 

Time to rejack my thread ;-)


I haven't spent any more time on the fuel issue as the timing chain needs replacing. I was able to drive the car from the front of the house around and into my backyard shop by filling the carb float (no fuel pump attached).


New fuel pumps are inexpensive so I'm replacing mine while things are apart and will start looking into whether there are problems in the lines/tank or just in my imagination.


In regards to the timing gears, am I correct in my understanding that I don't need to worry about engine position (ie TDC) as long as the alignment marks on the gears are aligned and replaced in the same position? With number 1 at TDC my marks are at 12 and 12 so I intend to rotate until they're at 6 and 12 before popping them off and installing the new ones.


In other news, I got my jammed door open after many shoulder checks. Reminded myself not to close it. Then closed it again. Damn. Fortunately it reopened easily later that night :-D (It now has shop cloth taped around the latch to prevent closing before repair!)

 

Assuming the old chain hasn't slipped or jumped a tooth, yes, that is correct. And 12:12 vs 6:12 is exactly the same. The crank rotates twice for every cam rotation. 6:12 is usually easier to see, however.

 

Thanks, Joe


I can't rule out a jumped tooth so I'm assuming that with #1 at TDC confirmed by piston position, misaligned marks would be indicative of a jumped tooth?

 

Just some closure...

Chain hadn't skipped, everything lined up and went back together nicely...discounting the hassle of installing the timing cover without removing the oil pan. No leaks so far.

I used an outboard engine fuel line pump bulb to suck gas through the line from the tank after pouring about 10 gallons of gas in. Gas flows no problem. Replaced the fuel pump out of spite. Got the car running and tuned just in time to take part in the Rod Run and Car Show I help organize.

 

what is # 2 for? Vent? Where does it go?

 

Yes. Later fuel pumps had a return that went to the fuel sending unit.