Hard starting

[ericcarr]

As some of you may know I’ve been trying to track down my hard starting issue I’m having with my 1990 sea ray with the 7.4 big block. I recently installed a new Holley 4150, 750 double pumper carburetor on it and in order to get it to start I have to keep turning the key on and on and on… I’m beginning to think I might have a spark issue. I regulated the fuel pressure down to the 6 psi from the 8 from the pump..is there a way to check to see if I’m getting adequate spark besides putting one of them online spark testers on it?

 

[alldodge]

A double pumper is not a boat carb, but that's a different issue then yours now

Being a 1990 you probably have a TB4 ignition, a serial number would verify.

have to keep turning the key on and on and on

What does this mean? Crank for a few seconds, off and repeat, or just keep cranking?

What is your procedure to start? Pump once, crank, or more then once?

 

[ericcarr]

Well I believe it is a thunderbolt ignition system. The motor that I had before the procedure was Pump It once or twice with the throttle and turn the key on and it will fire up, now that I have this different motor in it with different carbs that up it is extremely hard to start and my plugs are black and sooty

 

[ericcarr]

Oh yeah, I would just have to keep cranking it and eventually it would slowly start

 

[dubs283]

Oh yeah, I would just have to keep cranking it and eventually it would slowly start

Sounds like a flooding issue based on info provided. As dodge states, your carb isn't necessarily the right one for the engine, based on oem reference. I love holley carbs, great performance with ease of adjustment. You can tune the carb to the motor, 454 is one of the most forgiving engines out there and with some monitoring and adjustment you'll get the performance you desire.

FYI your motor with a thunderbolt ignition most likely came equipped with a quadrajet oem

 

[Scott06]

Well I believe it is a thunderbolt ignition system. The motor that I had before the procedure was Pump It once or twice with the throttle and turn the key on and it will fire up, now that I have this different motor in it with different carbs that up it is extremely hard to start and my plugs are black and sooty

Flooding or too rich plugs are fouled will always be a tough time to start. Get the carb straightened out test spark with gap tester. Might need to clean or replace plugs

 

[ericcarr]

Sounds like a flooding issue based on info provided. As dodge states, your carb isn't necessarily the right one for the engine, based on oem reference. I love holley carbs, great performance with ease of adjustment. You can tune the carb to the motor, 454 is one of the most forgiving engines out there and with some monitoring and adjustment you'll get the performance you desire.

FYI your motor with a thunderbolt ignition most likely came equipped with a quadrajet oem

Yes it did come with a Quadra junk carburetor on it when I got it.

 

[dubs283]

Quadra junk carburetor

Um.....perfectly fine carb when adjusted properly. Can actually get much better fuel economy at specific rpm over efi. Another conversation though.

Holley makes amazing carburetors, some dislike them cause they do "dump" fuel but fortunately your 454 loves fuel, and air, and timing both charged and naturally aspirated

 

[alldodge]

Your getting to much fuel, and the second pumper is just adding more. The 4150/4160 come in a variety of configurations (single, double, E choke, etc) and good thing is they are easily changed.


Do you know what jets are installed?

 

[ericcarr]

Your getting to much fuel, and the second pumper is just adding more. The 4150/4160 come in a variety of configurations (single, double, E choke, etc) and good thing is they are easily changed.


Do you know what jets are installed?

I do actually, I took the bowls off and there was 65 in the primary (front) side and 71 in the secondary (rear) side.

 

[ericcarr]

Another thing I might add is the problem that I am having is getting it started, all I am really doing is Pump It maybe once or twice and then turning the key over and over and over in order to get it to start. I’m really not even actually activating the secondaries

 

[ericcarr]

The carburetor in question is a 750 CFM double pumper with no choke on it right now

 

[dubs283]

Clear flood? Wot once throttle only, no pump. Crank engine til it fires then close throttle, best and really only way to clear flood

 

[alldodge]

Going to look up the sizes but your plugs are saying there is to much fuel

 

[alldodge]

Factory shows 72 / 84 or 73 / 73 with 6.5 power valve for 750 cfm

Looks like they have been changed, most likely for similar issues. The factory setup is to get it within range. Changing jets by +/- 4 usually means there is something else going on.

Yours being black might be the power valve is damaged, incorrect float height and carb is flooding. Incorrect timing would lead to pour performance, but it should still start.

Not having a choke would be bad for cold starts but should be fine once warmed up

 

[dubs283]

Yours being black might be the power valve is damaged

Especially at idle/low rpm. Don't forget faulty power valve gasket can/does cause rich conditons at low rpm.

One backfire on a holley equipped engine means 99.9% chance failure of power valve, ymmv

Once carb is set and motor is operating sound my next inspection would be a plug burn/inspection

 

[ericcarr]

Here’s what the new plugs look like..

 

[dubs283]

Would say most if not all are fouled. Buy new plugs but get engine/carb dialed in with old plugs. Can't see your issue being due to fouled plugs, seems more your issue is rich causing fouled plugs

 

[alldodge]

Your running rich, and while a 454 is listed to use close to 750 CFM, being a 1990 you would have peanut port heads. They do a nice job of low end torque, I'm not seeing that amount of CFM at WOT

Your plugs look fairly new and would clean up if we can get the fuel under control. Get the air fuel ratio in control, they will burn the black off and turn a nice cream color and you will pick up so MPG and HP.

As before the double pumper isn't doing you any good. A good Holley with vacuum secondaries would be better. It will only open as much as the motor can open it with amount of vacuum its producing. A Webar or Q jet would also work, I do like Holley but one backfire and there can go the power valve

Check those power valves out and see if they haven't ruptured.

 

[ericcarr]

I can visually look at the power valves and see if they are bad?