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Possible Fuel Starvation Issues


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Can anybody give me description of how the fuel system would be set up on an '89 Esprit with the GM MPFI system?  Specifically how the two tanks are connected and where the fuel level sender is located?  I've already figured out that the fuel pump is in the RH tank (because I can hear it.)

Here's the back story:  I bought an Esprit that has probably been mostly sitting for the last 5 years or so.  The owner before me only had it about 6 months and never even titled it in his own name, although I think he put a couple hundred miles on it.  I've been driving it around and probably put another few hundred miles on it in the last 6 months.  There were no issues for me other than the engine check light occasionally coming on when I 'got on it' with a slight drop in power, but then going off again after a few moments...only intermittently.

Well, I took the car to a slalom yesterday (where it did better than I thought it would...soundly beat a Miata that I was classed with), but by the 4th run, power started to cut out rather dramatically whenever I got on the gas.  I had to skip the fifth run.  On the way home, it occasionally felt like it was running out of gas.  i'd pull over and shut the engine off for a minute, then it would start right up and be on my way for many miles, until the same thing would happen again.  I made it home eventually.  It really felt like I was running out of gas.

Two additional things I noticed:  I started out with 3/4 of a tank as registered on the gauge, and somehow ended with 3/4 a tank, as though I'd used no fuel.  I could also hear a humming noise that I didn't notice before, that was obviously the fuel pump.  It almost seemed as though the fuel gauge was registering one tank, and that fuel was not flowing from the tank with 3/4 reading to the other tank where the fuel pump was.  Probably not the case, but i would swear that's what it seemed like.

Anyway, I ordered a new fuel pump, filter and screener (all less than $100), but they won't solve the problem if the passage from one tank to the other is blocked...

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  • Gold FFM

https://www.deroure.com/diagrams.asp?TBL=6482&MAK=1&MDL=45&SMA=0&SMO=0&ST=&SC=0
 

have a look at the parts diagram - there’s a lower link pipe between the two tanks. 
 

id be looking at the fuel pressure as a starting point

Only here once

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X2 on checking fuel pressure.

 

Good Job ordering a new fuel pump. It seems as if many of the Esprit GM fuel pumps are failing these days.

 

Hopefully your car's fuel tanks are not decomposing/flaking apart on the inside...some owners have been known to block off one tank to keep the debris at bay.  But if that IS the case, Boyd's Tanks in FL sell aluminum replacements.

Rusty Fuel Tanks.jpg

Atwell Haines

'88 Esprit

Succasunna, NJ USA

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Thanks for the diagram!

That is what I suspected...the float level is in one tank and the pump is in the other.  I feel I may have run the fuel out of the one tank, and the fuel was not flowing from the other tank fast enough to feed the pump.  That's why it felt like I was constantly about to run out of gas, but never did.  ANd the crap that's blocking the tube was probably also blocking the pickup and filter.

As for fuel pressure, I have a gauge that will plug into the shrader valve, but with the engine in the rear, it's going to be hard to see while driving down the road...

I'm going to pull that crossover tube and I guess i'll find out then it my theory is correct.

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  • Vulcan Grey changed the title to Possible Fuel Starvation Issues
  • 4 months later...

Hey, Tom,  so what did you find out?

Have you pulled out the pump? If you do you can put an endoscope to see how much debris there is at the bottom.

Edited by MrDangerUS
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It sounds like you had exactly what I had a year or so back when my Esprit was running much too fuel rich.

I'd fettled with my carbs and was fooled into thinking that I was getting better fuel economy, but because the fuel level gauge/sender was only one side (UK offside tank), although it appeared I had petrol, one side being blocked was starving the carbs of enough fuel, until the point the unblocked near side tank emptied completely and it stopped.

Perhaps your blockage is only partial?

Fill up the tank without the sender and it may push the blockage back into the tank with the sender (drain out some from the sender tank side if you have the equipment for this ?

If your gauge doesn't alter at all, then you clearly have a blockage?

 

 

 

 

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Hi, I have a similar problem but I think its my charcoal canister that are failing. If I fill the tanks to the top... the car runs lumpy and creates under pressure in the tanks. I also feels the fuelpump works hard to keep up. Have tried to source new canister but seems impossible. Any advice for me? 

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A possible solution put forward on another thread was to use a Duralast VC117 canister with a separate Delco 214-565 purge solenoid. Unfortunately there was no conclusion as to whether it was tried and did or didn't work.

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