Acceleration issues.

[YVRSpider]

Hi Guys,

I have an '82 Fi that starts up perfectly, and runs beautifully but recently, once the engine gets up to operating temperature I'll be driving along at cruising speed and everything feels fine but as soon as I hit the throttle and load the system the car starts to lose acceleration,sputters pretty aggressively feels like it's going to stall.(Sort of symptomatic of fuel starvation)
If I pull over, turn the car off and wait a few minutes, it seems to clear itself of the issue briefly but then it occurs again a few more miles down the road.

That being said, I've put in a new fuel pump (Bosch),new fuel filter (also Bosch) and a new fuel pressure regulator(Bosch).
I've checked the air filter and everything there seems to be in order in that department and I've run two cans of Sea Foam through the system.
When I first got the car about a year ago, I was having acceleration problems that I later discovered was caused from mineral deposits that had basically plugged the fuel supply nipple on the fuel tank to the point of total fuel starvation at anything more that 2000 RPM so I removed the fuel tank and had it flushed at a rad shop in an acid bath to clean it out and dissolve all sediment & mineral build up.
About 1 month ago I changed the fuel filter (which I had originally installed as soon as I bought the car so basically that filter was brand new and had no more than 400 miles on it. I started to feel the acceleration issues so I thought maybe that my fuel system might be picking up some dirt from the whole flushing procedure and low and behold, the fuel that came out of the filter looked like dirty mud puddle water. So I put a new filter in and ran it for about another 100miles. Today I took that filter off to see if the fuel coming out was showing any signs of being dirty but it looked perfectly clean and clear so I put another brand new filter in, took it out for a run today but the acceleration issue is still there and in fact, it's acting up now more than ever. I'm wondering if maybe the fuel system got dirty and has now plugged or is restricting the fuel flow through the injectors.
Any ideas, suggestions or thoughts on what this could be? Do you think it could be the F.Injectors are plugged?
Thanks for any and all suggestions.

[azruss]

I think you are on the right track. Doubtful that anything got downstream from your filter. I see 2 possibilities. since the filter is downstream from the pump and tank, it would suggest you have partial blockage at each. I had my tank cleaned and sealed at a radiator shop. let fuel sit in it for a couple of years. when i drained it out it looked like your mudpuddle fuel. I removed the tank and flushed it several times with water. each time in got clearer and clearer. upon inspecting the tank, i found it was very easy to dislodge any flakes clinging to the sides of the tank. It wouldnt take much of a flake to block any tight spot from the tank thru the fuel pump. since the fuel pump is new, i vote on the tank. I ended up replacing my tank with a new one.

[So Cal Mark]

if you've been putting dirty fuel through the injectors for any period of time, I'd remove them and have them cleaned

[YVRSpider]

Thanks Mark & Azruss, I think I'll look into getting the injectors cleaned out for sure and the tank crossed my mind as well. I think I might just pull the fuel lines and blow them out with air to purge anything that might be in there and basically start from one end and work my way right through the entire system to get it cleaned out.

[majicwrench]

How about TESTING SOMETHING first?? I would absolutely T a fuel pressure gauge in-line and test rather than guess. If fuel pressure drops when problem occurs, you have a supply issue. If pressure stays up, you have an issue on the engine end of things.
Keith

[redcars]

I would check the hose from the tank to the fuel pump if you have been running dirty fuel through it I had mine plug up at a tight spot and cause fuel starvation.

[YVRSpider]

Thanks redcars and majicwrench. I have to admit that the more I think about it, the symptoms seem so much like a fuel starvation thing and I'm also thinking that maybe the reason why it runs ok after I shut the car off is that perhaps their is dirty or debris that is getting sucked into the system and when I turn the motor off, everything settles and falls back to the bottom but soon gets sucked back up again once the pump is back in action. If I figure out what it is, I'll post the results. Thanks again

[So Cal Mark]

your original post said you had the tank cleaned already, is that not the case?

[YVRSpider]

Mark,
I had the tank cleaned in an acid bath to remove some mineral deposits that basically looked like a red clay color and had a texture similar to a dry brittle corral. It was like a dry sand cake for lack of better description that came out of the tank.
What I was thinking was, maybe there was a chance that some small bits of crud may not have been fully removed for whatever reason and is now floating around in there. Just a theory at this point but the "mud puddle" looking fuel that came out after my 2nd to last f.filter change concerns me and made me think that perhaps they didn't clean the tank out well enough after the acid flush.

[YVRSpider]

Well my suspicion seems to have been correct. I just removed the fuel sender unit and looked inside the fuel tank and there is basically a bunch of sand/sediment in the bottom of the tank and I'm guessing it's somewhere close to 1/8 - 1/4 cup in total. The good news is that I removed the hose from the tank to the fuel pump and it seemed like the fuel was very clean so I'm hoping that most of the crud has stayed in the tank but there's a pretty good argument that some of it must have gotten through the system to have caused a fuel restriction somewhere along the way. I've now removed the tank and seriously thinking that maybe a new tank is the best solution since there seems to be a lot of rusty looking stuff inside of it and a bunch of the sediment is caked on in all of the corners and seams. I just hope that it hasn't hurt the fuel pump or anything else for that matter. I'm guessing a complete fuel system purge might be on the horizon.

[So Cal Mark]

I'd definitely have the injectors cleaned. They have screens in them that can get plugged very easily

[majicwrench]

And I still would TEST SOMETHING FIRST at this point you are still guessing at what caused your problem. Sure, you can replace the tank, replace the lines, replace the filter, replace the injectors, replace the pump, and see if that takes care of it. Or you can run a few simple tests, find the issue, and fix it.
Keith

[moggyman64]

Hi YVS spider

Have you checked the vent pipe from the tank for blockage/kinks, could be a vacuum build up in the tank if the pipe is blocked, that would give the symptoms of fuel starvation also when you pull over and let the car rest for a bit then that would let the vacuum subside temporarily.

Regards

Keith

[YVRSpider]

Thanks Keith,
From what I can see, the vent lines are all clear and no signs of any kinks, that thought did cross my mind though. Thanks a lot for your input.

[moggyman64]

Sometimes things are not as they appear, a visual inspection does not always highlight the problem. Easy way to rule out a vacuum problem is to get a plastic temporary gas cap and drill a hole say 1/4" through it and test drive the car, that will only cost you a few dollars, if that does not resolve the problem then I agree with Mark, have the injectors cleaned.

Good luck

Keith