It wasn't pressure, it was vacuum. The fuel pump couldn't suck enough fuel because it was fighting the vacuum in the tank, and the engine would stall. That might be happening to your car, since you rely on minimal restriction between the tank and the fuel pump. I added a vent, and that's all it took.

I changed the tank when I went turbo, though.

So, I ended up swapping the main pump from the YROG, and putting it into the Smurf. This pump isn't leaking, but a few minutes after starting to drive it, the car started to hesitate, and the pump started to make quite a bit of noise. I right away pulled the fuel filler cap, and there was no vacuum that I could hear. After I started it again in the cold, and brought it into the garage, there was some pressure release when I opened the cap, but that could have been from going cold to hot in air temps.

In the end, it wasn't the pump all along, which sucks after pillaging the yellow car. While I haven't ruled out the vacuum issue Matt was talking about, I'm thinking after pulling the cap that's not it.

What function does the fuel accumulator perform? Is it before or after the pump in the fuel stream? I may check that next to see if its plugged....but why does the car run fine initially, and then hesitate after its warm?

Another idea I have is maybe the cold start is working, which is why it starts okay (not great), but another one of the injectors is pooched. Once the car is warm, the cold start isn't smoothing out the fuel delivery and so the car hesitates? The car still idles perfectly though, so that doesn't make sense.

In other news, the new steering rack was leaking a bit out of the pinion shaft seal thingy, so I swapped the cap off the old rack and measured both. The newer one was a few hundreths more worn, so I swapped in the older cap and bearing, and that seems to have stopped most of it.

And, there is a Thule Summit roof box on the car now. Got it used for a good price, so I'm happy.

The accumulator is basically a variable size cylinder with a piston and a spring. It serves two primary functions:
1. To smooth out fuel delivery pressure. If you stomp on the gas in a k-jet car, you need to have the main line pressure remain constant while the exposed area of the metering valves changes. This variable size spring loaded cylinder changes volume to keep the pressure constant until the fuel pump and line pressure regulator valve in the fuel dist can "catch up."

2. To maintain a rest pressure of ~40-45psi so that you don't get vapor lock and a car that is really difficult to start hot or within a few hours of runnning.

In my experience, accumulators either work or they don't. Usually they will leak out of the hose that goes back to the fuel level sender if they are junk and cause some odd warmer start symptoms.

It is good you have eliminated the main pump. I suspect that the main pump is working too hard. Without a pressure gauge or pulling the fuel return hose off, I couldn't really say what is happening, since that is usually how I diagnose them. Still, I suspect that the inside of the fuel tank is probably really nasty if the car has been sitting and you'd want to blow out the lines with air and change the fuel filter several times at minimum and also see what the line pressure does when you drive the car and all this is happening (I usually just take the volvo gauge and put it under the passenger windshield wiper...real safe I know).

Cool. Thanks James.
I definitely need to check line pressure, and test a few other bits. I'm guessing I can't just grab any old pressure gauge eh? Hopefully I can borrow a K-jet one from someone at some point.

Check a few other things yesterday and today. I changed the pump relay. No change. The auxillary air valve appears to be working. It opens to about 2/3rds the the size of the inlet/outlet, and then closes once cold. Not sure if it should open more than that. Anyone know?

I tried a another pump again tonight. Same thing happened, with and without the gas cap open. Upon initial startup, the car revs freely up to 6 grand. After a few minutes, the hestitation starts. Even not under load, the engine will hesitate and pop all the way to 4500 at most....won't go past that.

I changed the CPR for a later model to see if that might be it....no dice as it just blew fuses...guess that doesn't work. (Craig will be happy to hear I changed the CPR, tried running the car, and put the old one back in in 1/2 an hour). Next up is changing the fuel distributor with a spare, checking the injectors, and changing some if need be as I've got a few spares. I also pulled a spare accumulator, so that can be changed if need be.

I'm beginning to think my low idle at startup, and poor running after a few minutes are linked. Very suddenly, the pump begins to make more noise, and the car begins to run more rough. This only happens after warmup.

The question is: if there was a blockage after the pump, would it start working harder and thus make more noise? I understand if there was a blockage before the pump (ie. in the tank) it would have to work harder to overcome that. But I hadn't thought much about after (ie. if the distributor is blocked in some way.) Ideas?

Not much else has happened. Pulled a few more bits at the wrecker....piece off the door handle, and put that in along with the front signal trim and a few badges. Good times.

Sounds like there is a blockage before the pump. I presume you've checked the line back to the tank to make sure there aren't any kinks in it. How difficult is it to check the tank pickup? I've never played with a B20 240 tank. Actually, that's not right. I've pulled one out before but I never looked for access holes...

I've got the K-jet fuel pressure gauge setup. I'll try to remember to bring them down Friday...

Have you filled the tank yet? Does it happen at full tank or does it start at a specific level? I know you haven't driven the car much yet...

Noise at the pump is usually from cavitation, separating air bubbles from the fluid. The only way for that to happen is a pinhole in the supply hose, pinhole in the dip tube, or too much restriction on the inlet of the tank. Possibly a chunk of crud or whatnot is plugging the inlet of the dip tube at the bottom, and you'll never know because it's not removable (I think).

When testing fuel pumps, one of the tests I do is to do a deadhead pressure check - connect a funnel and hose to supply fuel to the pump, and a gauge to the outlet of the fuel accumulator, and nothing else. The pump will run up to 150 psig and then it labours while the internal relief valve opens. The accumulator or any of the fittings shouldn't leak and you should be able to shut the pump off and it'll hold pressure indefinitely. If it passes that test I consider it good, unless it's making lots of noise during the pumping phase. The point is, no - the pump doesn't make more noise when the discharge is blocked.

I've got a tank from Dale's '85 245 and I'm sure I can scare up a fuel level sender if you need it. The pump is up to you, though I might have one of those too. The swap isn't bad - drain your old tank, drop it, install the new one. Leave the filler neck installed, but the rubber grommets around the neck can be a small struggle. Wire up the pump and you're set.

This sounds like a pretty good fix. Greg and I discussed the possiblilty of stuff in the tank the other night. The car did sit for 12 odd years before being brought back to life, so chances are there could be some crap in the tank. He's got it plumbed right now with some fancy braided stainless line - so it's not leaking or pinched.

It does seem like the old Smurf needs to have every passage cleaned out prior to releasing it's grip on retirement...do you think it knows that it's now a winter car?

HA! likely!

Try blowing compressed air back through the lines between the pump and the tank? Take of the filler cap first. That might move some crud away from the inlet. Might also stir things up even worse in the tank too...

I put a new in-tank pump in that 245 tank a couple of years before I pulled it off the road so that will be healthy. Make up your mind on that asap. I'm coming down Friday...

You may have put a new in-tank pump into the 245 before taking it off the road, but you put the same pump into the 122 before putting it ON the road.

Tye's car sat in damp Oregon for about 3 years and in california in storage for about 8 years before that. The tank had to be replaced. It looked like a boston tea party of rust flakes. His 242T was an '83. Your '75 has been sitting 10 years probably not in california. I'd be shocked if it didn't need the fuel tank replaced or like acid dipped and zync treated (easier to just find a late model tank).

Plus, you should SEE some muscle cars' fuel tanks - years of leaded fuel make a pretty sweet varnish on the inside of the fuel tanks, and it seems that unleaded fuel lifts this varnish off in sheets. I've seen pictures of a guy holding up what amounts to a sheet of lead 1/8" thick.

Yeah, and I suppose this car would have had leaded fuel for the first while eh? Crazy.

Thanks to all for your responses. I do appreciate it.

Dale: the line before the pump between the tank has been replaced, so it should be clear. The feed line out of the tank comes from the left side, mid-way up. Its just a 90 degree fitting, which I believe is threaded in. I'll check tonight, and maybe seet if I can stick some wire up there to see if its clear. If you can bring your pressure gauge tester on Friday, that would rule! Thanks!

Matt: I haven't filled the car up yet, no. I siphoned 10 litres of gas out of the YROG, and have added 20 litres from a jerry can. I doubt I've run the car for more than an hour yet, so I've likely got 10 or 15 litres in there. Not sure how that affects running. So it is likely before the pump...excellent, thanks for the explanation. Makes sense now.
If you are willing to part with that tank, (or is it Dales?) I'd be more than happy to take it. That would work out perfectly. And if you have a sender, even better, as mine is pooched. Its funny as even one of my manuals describes adding an in-tank pump to the early cars. I guess it must have been done often.

Craig: Yeah, it seems like every freaking line in this car was plugged. Meh. I'm gonna show it the beans once its on the road. Actually, did I mention I found a manual for an antique radar detector in this cars paperwork?! I laughed my ass off! Seriously, how fast does this thing ACTUALLY go? 115? BWAHAHAHAHAAA!!! The previous owner must have been in a hurry to get to Brocket.

James: Yeah, I've seen that with West coast cars before. My '79 244 had a useless tank in it, as it had sat off and on for years in Vancouver. Nothing but rust on the inside. Whereas my '79 245 w. 400,000 k+ on it was clean.

There is a tank in the back of the truck that is complete...sender, pump, the lot. We can't figure out what it came out of...

What the hell....the gas tank on my 242 went missing last night!;-)

Good luck Greg, pretty straight forward job to do, and hopefully it gets you running!