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Discussion Starter #1
Been having some issue with my 78 spider. After driving a good distance on hot (85+) days the fuel will get a quick cutout at high revs and get worse the more you drive. It will get to the point that when you step on the gas pedal the fuel will cut out almost instanstly. You can still drive it but you have to go slow and be very careful on how much you step on the pedal. We have replaced the rear fuel pump and front fuel filter so far and nothing has changed. If anyone has any ideas on what could do this please let me know.

If you shutoff the car let it get cold and drive the issue goes away until you drive for a good amount of time on a hot day. I haven't been able to get the issue to happen on cool days.
 

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Have you made any changes prior to the symptons that could have put your fuel lines, etc. closer to a heat source? If so, it may be vapor lock.

Or maybe the temp sensor...
 

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Three questions for you;

1) does the low fuel pressure light come when the symptom occurs? (actually, does the light work at all. It should come on for about one second when the ignition is first turned on, then go out)

2) has the rear fuel filter been changed?

3) has the vehicle been retrofitted with an in-tank boost fuelpump?

And welcome to the BB!
 

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Discussion Starter #4 (Edited)
No changes were made before this started happening. We haven't changed the rear fuel filter yet but I am hopeing to get a chance to do that this weekend. Also it is a standard fuel pump that we replaced. Also the light on the inside of the car doesn't work anymore so I cant tell the fuel pressure from that.
 

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Fuel Pressure light

Do yourself a favor. Fix the light or put a fuel pressure gage in the fuel line during diagnostics. It will save you a lot of time in locating the trouble. It could be the bulb or the pressure sensor on the top of the main fuel filter.
 

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I had a similar problem a few years ago. The worthless inertia switch was going high resistance when it got hot. Check to see if your fuel pump is running the next time it happens or have a jumper ready to short out the inertia switch contacts.
Ed Prytherch. (on vacation in Italy).
 

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It is critical that your fuel low pressure light be operational. Running the Spica pump on low fuel pressure can cause rapidly increased internal wear in the pump. This can require a very expensive and unnecessary injection pump overhaul (about $750, w/0 labor).

Go to www.wesingram.com/hp.htm and download the Fuel Systems Diagnostics Guide. After reading the guide, come back with any questions you may have. Dirty inertia switches can cause a voltage drop to the fuel supply pump. I'll need to know exactly what kind of pump is in the car now. Some owners install inappropriate generic fuel pumps that have insufficient fuel pressure and/or capacity.
 
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