acceleration issues

[tuns0ffun0]

OK, so this isn't about a chevette but you guys are pretty awesome about helping. I recently picked up an 83 mustang gt convertible 5.0, which is apparently a rare car(reason for buying). I have done some minor work to it to get it running right. I routed the vacuum lines and blocked off the unnecessary lines.

The problem I am having is it stutters during gradual acceleration but when I give it considerable throttle it runs like a champ. I started doing research and everything I was reading was to check vacuum pressure. The vacuum is running right and steady.

Next we checked fuel pressure. The stock mechanical pump puts out 7psi, which is what this one gives. It has had an edelbrock 600cfm put on top. Researching the carb, it wants a mamax of 6psi. I ordered a fuel pressure regulator and while installing(no instructions included), it has one inlet, two outlets, and another smaller connection(maybe for vacuum?). One of the outlets has the gauge on it. We installed it leaving the smaller other connection unplugged. The pressure was set to 5.5 as per edelbrock recommendation

Took it down the road and it ran better until it just died. Took the FPR out and it started back up and drove back to shop acting up again. My main question is, does anyone have experience with using a FPR on a motor that has always been carb'd? And any other recommendations would be great.

Thanks guys

[tony22]

the fpr has to have vaccum hooked to it or it dosent regulate the fuel it shuts it off that why they are on fuel injected engines but i think it has to be low to high as the engine rpms go up so find one that does that and you should be fine but it sounds like the jets are pluged a little to me when you go full throttle is sucks more fuel because of vaccum pull mabe that will help

[DOCTOR FIELDS]

A FPR is simply a spring and a diaphram. When hooked up to vacuum, at idle (high vacuum) the diaphram restricts fuel flow, as more throttle is applied (low vacuum) the diaphram opens up allowing more fuel. In your case, without any vacuum, it should be opened up, so im not sure why it died. When you adjust the screw, all your doing is adjusting the tension on the spring making it easier / harder for the diaphram to move under vacuum.

I'm with Tony, the main circuit in the carb. is most likely clogged somewhere. Does it idle ok? Sounds to me when you hammer down on it, the power valve circuit is working, adding enough fuel for it to run properly. I would take the carb. apart, give it a good soaking and use compressed air to blow out all passages. If the car sat for any period of time, especially with ethanol based fuel, it doesn't take long for it to start oxidizing the inside of the carb.

Let us know how it goes!

[tuns0ffun0]

the car idles like a champ. I just stutter only when slowly accelerating. Gonna try and get back after it tomorrow. I really appreciate you guys input.