Starting problem after replacing fuel lines

[David T]

Refer to D:02:01 Note 10 for torque specs for the fuel lines. These are for use with new copper seals. If the joint should leak check for scoring, unevenness or dirt. Certainly the lines should not be under additional stress by having been twisted, bent or kinked. Another reason a joint can leak is, when assembling it, you accidentally miss a copper seal or use more than 1 per side. It doesn't take much additional torque to break the banjo (hollow) bolts so don't overtighten them to stop a leak. Leaks are hard to miss, you can smell them, even if you can't see them. A tiny leak at these pressures and the fuel will atomize and not always be visible. There can be NO leaks. While a leak can cause hard hot restart problems it should not cause a hard cold start problem. Recheck that you have the lines correctly connected and routed.

[Stainless]

Refer to D:02:01 Note 10 for torque specs for the fuel lines. These are for use with new copper seals. If the joint should leak check for scoring, unevenness or dirt. Certainly the lines should not be under additional stress by having been twisted, bent or kinked. Another reason a joint can leak is, when assembling it, you accidentally miss a copper seal or use more than 1 per side. It doesn't take much additional torque to break the banjo (hollow) bolts so don't overtighten them to stop a leak. Leaks are hard to miss, you can smell them, even if you can't see them. A tiny leak at these pressures and the fuel will atomize and not always be visible. There can be NO leaks. While a leak can cause hard hot restart problems it should not cause a hard cold start problem. Recheck that you have the lines correctly connected and routed.

The manual shows different torque specs for different fuel line bolts (M8, M10, etc.), but the bolts themselves are all just labeled as "hollow bolt" in the parts manual. How do I know which ones are M10's, for example?

[Ron]

The "M" is for "Metric". The number following gives the diameter of the threads in millimeters.
E.G., A M10 will have a Thread Diameter of 10mm.

[DMC-81]

The "M" is for "Metric". The number following gives the diameter of the threads in millimeters.
E.G., A M10 will have a Thread Diameter of 10mm.

+1 . Also, for future use, to help figure this out quickly, there is a simple plastic tool available at your local hardware store. I picked up this one from Home Depot several years ago:
https://www.homedepot.com/p/8-11-16-...O-02/100186831

This is a tool that that gets a LOT of use. Definitely worth the $2

[Stainless]

+1 . Also, for future use, to help figure this out quickly, there is a simple plastic tool available at your local hardware store. I picked up this one from Home Depot several years ago:
https://www.homedepot.com/p/8-11-16-...O-02/100186831

This is a tool that that gets a LOT of use. Definitely worth the $2

I picked one of these up the other day. This is perfect. Thanks!

[hippieman9]

Ok Looks like i am having the same issue now too. I replaced all my fuel lines from the filter back, a new filter and elbow from DPI and Daves RPM relay. I had to crank the car a lot to get it to start the first time after the replacement, That didn't surprise me as I figured it would need to prime and purge the lines and get the air out. It would then fire right up after running for a while with no issues. I then had to rebuild the brakes and it sat for a week or 2 till the evening when I went to take it for a test drive and I had to crank it a few times before it would start.
When I had the original lines on the car it always started right up no issue. I am going to check the items you have all mentioned in this thread. My one question is how does the mixture effect the way it starts with new fuel lines? Why would the new fuel lines require a different mixture?

Thanks!

[Ron]

My one question is how does the mixture effect the way it starts with new fuel lines? Why would the new fuel lines require a different mixture?

Thanks!

IF the original and new lines had no leaks or restrictions, there would be no change in the mixture (nor in anything else concerning starting/running).
Since it ran well before, I'd suggest checking that your injectors/boots are tight and sealing properly, vacuum lines are still intact, and that the cold start valve is actually spraying. Then, if no luck, report back in a new thread with your findings...

[lazabby]

Similar thing happened to me. Replaced fuel line, injectors and CO2 plug and the car ran worse than before. Anyway, about a month ago I was having an issue with a hard start when the car was both cold or hot. I feared it might be the accumulator. It turned out to be the "plunger bolt" or fuel pressure regulator that is in the fuel distributor. It has two o-ring on it. When I took it out, one of the o-rings was flattened and the other one had started to break apart. I replaced both and the car now starts immediately. If you have a hard start issue, be sure to check that out.

https://www.deloreanautoparts.com/de...egulator-1.jpg