89 mustang 5.0

10

Asked by Aug 08, 2015 at 08:33 PM about the 1989 Ford Mustang LX 5.0L

Question type: Maintenance & Repair

My boyfriend has an 89 mustang with a
super charger in it. It runs fine with the hood
up but about 5 to 10 minutes with the hood
down it completely turns off like you shut
the key off.

14 Answers

24,445

Has he tried adjusting IAC idle air control or cleaning the MAF mass airflow sensor. Both are easy to check and or clean / replace.

66,065

Sounds like the ignition control module is getting hot and shutting down. When it quits, spray some starting fluid down the throttle body. It should run a few seconds on the starting fluid. If not, you have no spark and the module is the prime suspect. HTH. -Jim

92,905

Diagram

10

It's killing the fuel pump. It turns the fuel pump off

24,445

Thats an easy fix and it would be a good time to upgrade to a more powerful fuel pump. Dont forget to change fuel filter and maybe the injectors depending on what the set up is.

92,905

Check relay and the inertia switch, both are known failures, the inertia switch tends to melt the contacts inside the plug.

10

The fuel pump is still working to start the car and everything. If he takes the hood off the car it will stay running no problem it is only turning off like this when the hood is closed

92,905

So it is either vapor locking, or the relay is thermally failing. It might be a good idea to replace all of the relays just to eliminate any secondary problems.

10

He thought it was vapor locking so he rewired the fuel line that was sitting right next to the turbo.. That didn't help. Where is the relay located? I looked at a couple other sites and it says under the drivers seat but there is nothing there

92,905

How heavily was this modified? Mustang 5.0 was never turboed from the factory.

66,065

Here's a thought, is it possible that a wire is getting pinched when the hood is closed, creating a short, and killing the ignition or fuel pump? HTH. -Jim

10

That's what he originally thought was going on so then he rewired the fuel line and it didn't help. It's decently modified. Pretty much everything under the hood is after market. It's supposed to get almost 400 hp. We can't get it to that point because it doesn't stay running long enough to have fun with it. He is also a mechanic but this one seems to be stumping him

1 of 1 people found this helpful.
66,065

Since it takes a few minutes for it to quit (I just reread your post) I'm still thinking something is getting hot and shutting down. Have you tried spraying starting fluid down the throttle body when it quits? That'll narrow it down to a fuel or ignition problem. If it'll run on the starting fluid it's a fuel problem. If not, it's an ignition problem. HTH. -Jim

10

He knows it's a fuel problem

Your Answer

Add photo

Related Questions

Mustang

Looking for a Used Mustang in your area?

CarGurus has 45,735 nationwide Mustang listings starting at $1,999.

ZIP:

Search Ford Mustang Questions

Ford Mustang Experts

#1 Tom Demyan
Tom Demyan
Reputation 4,270
#2 Bob Beaman
Bob Beaman
Reputation 1,210
#3 COMETGUY61
COMETGUY61
Reputation 1,060
View All

Related Models For Sale

Used Chevrolet Camaro
226 Great Deals out of 30,943 listings starting at $1,217
Used Chevrolet Corvette
119 Great Deals out of 20,753 listings starting at $3,000
Used Ford F-150
2,191 Great Deals out of 206,316 listings starting at $1,499
Used BMW 3 Series
971 Great Deals out of 31,729 listings starting at $1,000
Used Jeep Wrangler
276 Great Deals out of 18,163 listings starting at $2,950
Used Honda Civic
654 Great Deals out of 88,603 listings starting at $995
Used BMW M3
45 Great Deals out of 1,517 listings starting at $5,800

Used Cars For Sale

2017 Ford Mustang For Sale
31 Great Deals out of 23,103 listings starting at $18,779
2016 Ford Mustang For Sale
160 Great Deals out of 5,276 listings starting at $16,991
2015 Ford Mustang For Sale
58 Great Deals out of 3,525 listings starting at $13,988
2014 Ford Mustang For Sale
51 Great Deals out of 3,152 listings starting at $9,000

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.