# Starts sometimes / Stutters under load or heavy acceleration



## Whitey(banned)vr6 (Sep 29, 2003)

Trying to cross a few things out before jumping the gun. Heres my issues. 

Cold Start - Starts but barely idles/rough idle for about 10 seconds and then idles fine.
Hot Start - Wont Start, Starts and instantly dies or Eventually Starts
Driving - Runs great while just cruising or above 3500rpm. Below that, and under load it stutters to accelerate. Entire car will buck pretty hard.

I'm assuming its the inline pump (already replaced in-tank). The pump whines pretty loud and can be heard in the car. Is this normal? I had a Bosch 044 in my race car and I could always hear it and assumed this was normal but Cabby-info.com says if its whining then its on its last leg. 

The only reason Im weary to replace the pump is because I just replaced the ignition switch recently and just want to make sure i couldn't have received a faulty one. I don't believe this is the case because the issue has progressively became worse but any insight would be greatly appreciated. 

Could this be something else like timing or ?? Thanks!


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## RM21 (Jul 13, 2014)

I have the same issue.. Let me know if you figure it out... Already done the in tank as well.. Did the high pressure about for years ago.. Mine isn't as bad and some days it's fine.. And others is horrible. No choice but to matt the throttle to get it to act half way decent.. Today was a good although the only thing I've done recently is change all the shifter linkage.. So moving wires and coolant tank etc.. I am leaning more towards a loose connection or vacuum than pump.. I'll let you know if I find the silver bullet


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## kwak (Apr 7, 2005)

You should be able hear the pump for the first 2 seconds when the key is turned on, but when the engine is running you shouldn't hear the pump from inside the car. I assume your race car has no interior so you will hear the pump more.

When the engine is running, place your hand on the inline pump. You'll be able to feel if it is bad by the kind of vibrations.

When my inline pump was going bad it gave the opposite kind of running problem. The engine would bog down if I tried opening the throttle more than halfway or tried running the RPM above 2K. I had a severe lack of fuel. And from the noise of the inline pump and touching it something was definitely wrong with it.


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## Whitey(banned)vr6 (Sep 29, 2003)

Damn, now I'm questioning what to do!


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## Zenith451 (Nov 8, 2014)

*Stutter under load*

Driver,

If the unit runs fine at speed as indicated then fuel delivery is not an issue. If you "roll" on the throttle it probably doesn't buck as much if at all, punch it and it feels like a piston is coming thru the hood? 
Pull the plugs and check resistance between the tip of the firing end and the boot end of the plug, make sure the plug isn't open, indication of mfg issue or broken internal welds.
If you have resistor plugs then you should see a couple of K ohms tops with a DVM. Non-resistor plugs should be zero or a couple of ohms. 
If plugs test well then I'd suggest you replace the Cap, rotor and wires. My 88 Fox had a similar issue, I replaced 
cap and rotor and it improved, fresh wires did the trick. The wires looked great but were breaking down internally, heck they were "only" 12 years old...


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## Whitey(banned)vr6 (Sep 29, 2003)

I replaced cap, plugs, wires and coil... Still no love... Guess it could be a rotor but judging by the 2nd problem I'm semi-convinced it's a leaky or malfunctioning cold start valve ? Any thoughts 


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## Zenith451 (Nov 8, 2014)

*Cold start injector?*

Driver,

It "could" be the 5th injector, I've never seen a leaky one.,easy to test though. Start the car cold, count to 30, shut down, pull valve, if it's wet or dripping that'd be the culprit. I'd test the sparkplugs as outlined 
above also, it seems like parts quality has declined and you could have some bad units out of the box.

Good Luck


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## Whitey(banned)vr6 (Sep 29, 2003)

So, I was driving it last week and decided to drive it longer than normal with the current issue... At about 30 mins it started bucking really bad... By 35 it stalled going up hill, it then would not start.... When putting the key in the ignition into the on position the fuel pumps no longer primed... I tried swapping the fuel pump relay with the load reduction and same issue... Does anybody have a clue to this horrible nonsense ?!?! 

I thought it might have been the hall sensor so I replaced the distributor and did a timing belt today ... No change



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## RM21 (Jul 13, 2014)

*Fixed..I think?*

So I decided to go all in on the cutting out problem. because it felt like i was running out of fuel..made worse by trying to take off quick..
Here s what I did. first replaced the external pump..but also replaced the hose that feeds it. its a pain because the hose is really tight. I warmed it up with a torch and forced into onto a old pump i had laying around to pre form it so to speak. next I went back into the in tank pump..this is critical. after changing the external pump it was still loud, like it was getting air..so when I removed the in tank the hose was dry cracked throughout..new hose there as well. also pay attention to the scale buildup on the yellow wire grounding back to the in tank assembly.. remove the blade connector and clean up the contacts..mine was loose which i think was making a intermittent problem so the pump was on then when fuel sloshed forward or around the tank it would loose ground starveing the external pump. also make sure the clamps are tight in between the pump and the metal discharge tube.. all these things I have gone through and now I have no more bucking under heavy load or take off..good luck!


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## Whitey(banned)vr6 (Sep 29, 2003)

First off I would like to give RM21 a big shout out for helping me fix the biggest headache of a problem I could have ever expected. 

First off... I replaced the following during the diagnosis:

Ignition coil
Plugs
Wires
Cap
Rotor
Distributor
Fuel accumulator
Both fuel pumps
Ignition switch

The final fix was : 14" of fuel line which runs from the top of the intank pump and down to the metal line which feeds the inline pump... This line is hidden between the tank and the frame and is not inspect able... Having done everything else... I decided to listen to RM21 and give it a shot... 

Although there was no leak in my line... The cracks were significant enough to cause an air leak making the pump work way to hard... As soon as I started the car I knew the problem was gone because I couldn't hear my pumps at all... 

Here's a pic of the line for reference










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## RM21 (Jul 13, 2014)

Crazy when you know you got it! The pumps are almost silent.. I rode around with my inspection cover off for awhile because I couldn't believe how quiet they can be! 

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